Valve periodically asks users to respond to a survey that automatically collects information about their computer hardware, to better understand their target audience for new games.  This represents all Steam users who said "yes" to allowing Steam to collect information about their computer.

http://www.steampowered.com/status/survey.html

Highlights:

64.5% of respondents have broadband (768kbps or higher) (less than I expected)

44.5% have 512 to 999 MB of RAM, 29.57% have 1 GB or more

46.5% AMD, 53.5% Intel (LOTS more AMD than I expected)

75.4% 1 CPU, 24.1% 2 CPUs, 0.5% 4 CPUs

57.7% nVidia, 35.2% ATi, 7.1% Other

Top 5 graphics cards by popularity:
GeForce 6600 (w00t for me)
GeForce 7600
GeForce FX 5200
GeForce 8800
Radeon 9600

DirectX 9 Shader Model 3 rendering path is dominated by nVidia cards, Shader Model 2 rendering path is dominated by ATi cards.

2.31% of respondents have DirectX 10 GPUs.

ATi respondents have somewhat more recent drivers than nVidia respondents.

83.6% have a 4:3 display, 17.4% have widescreen

51.75% of nVidia respondents have PCIe 16x

1.19% of respondents have more than one GPU (thank God)
Of those, 99.4% have 2 GPUs, the rest have more
95.56% of multi-GPU users are using SLI, 4.44% are using ATi Crossfire (I had no idea Crossfire was doing so poorly)

The vast majority (I'm not going to add it up) of respondents use onboard sound.

90.3% XP, 8.0% Vista (more Vista than I expected)

60.4% of respondents have their language set to English.

95.4% of respondents have DVD-ROM drives (so can we PLEASE never release another game on multiple CDs?)

The only thing I wish they had shown that they didn't show is whether users were running a 32-bit or 64-bit operating system. 

That is a very high percentage. It would have been interesting to see what percentage of users had AMDs when they were still faster for gaming than Intels.

You could even, on a limb, suggest that a good portion of the 24.6% of multicore owners were originally using AMDs. Just goes to show how much of an impact AMD really created in the PC enthusiast/gamer markets.

Can't wait to see what Phenom can achieve in terms of speed and efficiency, given that AMD stated that Barcelona beats Intel equivalents on certain benchmarks. Of course, Intel will probably move to Penryn soon enough, negating any speed benefits that AMD's new generation of chips currently have, but who knows?

I do hope that both Intel and AMD run neck and neck - that will undoubtedly lower prices, improve performance, and benefit us, the consumers.

Steam polls are somewhat scientific towards gamers. The numbers are obviously NOWHERE near correct to what the rest of the world uses. We all know Intel dominates the CPU market, we all know that most PC's bought by the "average" user from places like Dell, HP, Acer, Gateway, etc don't have video cards.

It paints a good picture of what the demographics are for GAMERS, but not the world.

If only the same can be said for video card department...

doesn't seem like we'll see highend cards lower in prices anytime soon.

 Well considering this a videogame website...I don't care what Mr. Smith down the street uses for a PC..

 Considering the topic doesn't mention anything about who the TARGET demographics are, it's unscientific.  If the title was Steam Demographics for PC hardware, then I wouldn't care.  It's a poll in a niche market, that doesn't represent the entire market.  That's my point.

I'm guessing a majority of regular PC gamers have Steam for at least one game. It helps Valve develop games that cater to what the public has or will have soon related to PC hardware...and obviously it helps other developers who check out this info as well.

I'm surprised that the average amount of RAM is so low...I've had 2 gigs for about 2 years now.

That would be why my first paragraph explains the survey methodology.  This is, you know, a gaming forum, and I figured people would be interested in knowing some demographic info about gamers' PCs.  Valve certainly is, and I think other game publishers should be as well.

If you look at the survey results, I think they represent the PC gaming market rather well.  You can see that most people don't have multicore CPUs, the vast majority don't have SLI or Crossfire or a DX10 GPU.  The most popular graphics card was a midrange card three years ago.  Most people have less than a GB of RAM.  I think it's interesting that PC gamers are not as upgraded as people seem to think they are.  Valve seems to be one of the few developers that understands this and designs their games to run very well on average (meaning midrange from three years ago) hardware.

Anyway, what you said in your first post is all I intended to show.