How about the fact that Valve said that Steam sales were going to pass their Retail sales soon? They said that 9 months ago (May '08), so it's logical to assume it has already happened:

Gabe Newell:
"We see sub ten per cent growth rates in our core, packaged retail business," Newell said. "Right now we're seeing close to 200 per cent growth in the alternative ways of connecting with customers.

"It will actually pass over in the next three months, how much of our business is coming from retail versus how much is coming from other channels,"

http://www.eurogamer.net/articles/digital-overtaking-retail-for-valve

And as for COD4, I have always said that the PC version of COD4 reached/will reach 10 millions copies sold. COD4 is still full priced on PC, and just yesterday I saw it once again reach the Top10 Sellers on Steam, 15 months after it's release. I also remember that Actiblizzard said on their Q2 09 FY Report that COD4 was still one of the top5 selling PC games of that quarter.

EDIT: I thought you were talking about L4D, on the DD sales thing. The calculations were rough and not intended to be used as an estimations of copies sold, but it shows that unless the average L4D player is playing like 5 hours every day, the PC version outsold the Xbox 360's handsomely. I remember I used such calculations on COD4 in fact, and it got around 15 or 18 millions copies sold on PC. But again, only showing the popularity of the games, not the sales.

Of course Valve games are going to sell like crazy on Steam. CoD4 on the other hand will absolutely not sell via DD anywhere near as well as retail.

And once again, you bring your speculation and imaginitive calculations into how much CoD4 sold on pc. As of June of last year CoD4 had 10 million units sold, with the 360 version doin the best. If we were to assume the PS3 version were to have sold 1 copy and the pc version sold 4,999,999 copes to the 360's figurative 5,000,000. That would mean it would have to have sold another 10 million copies on pc in order to reach the numbers you gave. So in the amount of time from July to now, the same amount of time from launch to June, COD4 would have increased its sales rate two fold. Piracy would be the only thing giving credence to your number, but even then that would be stretching it. Also, you seem to assume that sales of the 360 version have stopped as well. 6 months after the release of CoD4 the 360 version had sold the most. That is unlikely to have changed.

Here is what is helping the whole COD selling better on console versus PC arguement. It is available on two consoles which helps but doesnt mean that if L4D was released on the PS3 it would help in anyway.

Also this is realistically an argument of PC vs Console sales versus DD vs retail as the PC version is available both ways. There is no real way to state if COD4 PC wont or isnt outselling the console versions just like COD:WaW will probably be outsold by the PC version at some point. It is just a matter of time considering console software sales typical die pretty quickly. Even the games with legs die in a few months while PC sales stay pretty steady mattering price reductions and popularity. Half-Life 1 is a perfect example of this since it sells over 1 million copies through retail and Steam sales a year, there are few games that can attest to doing this,  and most of the ones which can attest to steady sales like this are mostly PC titles.

Yes, that could very well be the case. But there is a lack of evidence to support your points. Making a blanket statement such as all pc games will outsell their console counterpart is complete fallacy unless you have numbers to back you up. Until NPD releases their DD estimates, this is all just speculation and baseless claims.

It's not conclusive. When Activision claimed COD4 sold 7 millions, they only took into accout the sales from the top western console-centric countries and very few PC-centric markets: North America, UK, France, Germany, Italy, Spain, and Benelux. They could've very well done the same for the 10 millions figure, which would basically halve the retail sales of the PC version because it wouldn't include dozens of PC-centric countries. Also, they didn't include the sales of the MAC version.

Another thing is that I have never seen Activision include or mention the digital sales of their games on anything. So I'm not sure they would make an exception for COD4.

COD4 outsold Orange Box for months on Steam, and was the top-selling game for god knows how many weeks. It stayed most days in the top 5 sellers until COD:WaW released, but it still peaks shows up sometimes at 10th of Steam's top10 like yesterday. One last thing, COD4 sells on other Digital Distribution services like D2D, and unlike Orange Box.

shio is indeed using a blanket statement, having absolutely no facts to back up any DD sales claim he's making.

That's why I, and others at VGC (along with other DD leaders) are looking into exploring ways of aggregating Steam's sales numbers, in hopes of finding out how well they are.

If you want to use 18-24k concurrent users as being a massive number of units, projecting to millions of sales, I must ask what you think of Halo 3 and other games having 5x that many concurrent users at any given time.

Furthermore, what about all the 'other' non-Valve games on Steam that are reporting a few dozen, or hundred users at any given time like your much-touted AudioSurf? Wouldn't that equal out to just above 10,000 sales for such a game? If so, then I guess Steam is an utter failure at the DD model for anyone but themselves.

 10 million? Are you sure? So do you think it will outsell Half-Life 2? Impossible 

well thats never going to happen so the NPD is just going to become increasingly useless as DD takes over in the next 10 years during the transition.

actually HL2 has only sold about 6.5 million so far according to the internet so by the time COD4 sales 10 million on PC HL:2 will be like 12 million or more.

Oh, and concerning the penetration of DD services in Eastern Europe, and other areas:

Wouldn't it be a viable way to calculate how 'big' these markets are, based on the number of dedicated servers Steam employs? After all, if Eastern Europe is a huge market, Valve would need a large number of servers to handle the massive amounts of traffic:

http://store.steampowered.com/stats/content/

Australia - 9 (0 Valve Deds)
Bulgaria - 2
Cambodia - 1
Canada - 2 (2 Valve Deds)
Czech Republic - 3 (2 Valve Deds)
Denmark - 2 (1 Valve Deds)
France - 2 (2 Valve Deds)
Germany - 17 (4 Valve Deds)
Greenland - 1
Hungary - 1
Indonesia - 1
Ireland - 2 (2 Valve Deds)
Italy - 4 (4 Valve Deds)
Japan - 6 (6 Valve Deds)
Malaysia - 2
Netherlands - 15 (15 Valve Deds)
New Zealand - 2
Norway - 1 (1 Valve Deds)
Poland - 2 (2 Valve Deds)
Romania - 5
Russia - 5
Singapore - 4 (4 Valve Deds)
South Africa - 1
Spain - 4 (4 Valve Deds)
Sweden - 3 (2 Valve Deds)
Switzerland - 2 (2 Valve Deds)
UK - 11 (11 Valve Deds)
US - 63 (62 Valve Deds)
_______________________

Now, I must ask you: how is it that Eastern Europe is this whole big under-reported market, yet Valve, the biggest online gaming destination, has on a few servers in said markets? I mean, they have 60+ in the US alone, you'd think they could spare a few for these Eastern-Bloc PC paradises, right? Or could it be that they aren't as big as you think?