The fact that you say you never experienced ANY lag/disconnects shows you are not being honest.  They both use P2P so even on PSN you will have issues with lag and disconnects just like on 360.  From my personal experience and that of everyone I know that has the PS3 version, it is far worse online than the 360 version.  Where are you located?

They both use peer to peer. So any lag that can occur on PSN can also happen on Live. From my experience playing it on both it was far laggier on Live for the game that I played.

That being said I hate COD so will not purchase on any platform.

There both gonna be the same, IW isnt gonna let the 360 version have superior graphics and decline PS3 sales.

I never experienced any lag either (playing MW on PS3).  At least none I remember.  Are you sure maybe you aren't the odd man out here?  I don't remember reading anything about one being superior either, and I'm sure fanboys would've brought it up.

I'm sure I wasn't the one with the issues.  I played every other PS3 game I owned without a hitch.  I have 25mb/s download speed and 15mb/s upload speed.  There is no way I could possibly lag due to my own accord.

It varies.  You probably find about one or 2 laggy matches for every 10 good ones on Xbox Live just because of distance, poor host choice, etc.  On PSN it seemed like I couldn't find a single match where half the room wasn't yellow pinging.  Perhaps they have improved it within recent months.  I haven't played CoD4 in a year now on PSN and I haven't played WaW in about 3 or 4 months.

The reason my friend even bought a 360 was because he is a huge CoD fan and he was tired of never being able to play without lag so I showed him the 360 version and he instantly went out and bought a 360 with CoD4.

it's going to be virtually the same

*facepalm* people who can't read and don't know what they are talking about really shouldn't comment.

Matchmaking systems run on servers.  MS hosts the matchmaking system for all games even 3rd party multiplatform games.  On PSN, Infinity Ward has to dedicate some of its own servers to do matchmaking for their PS3 games.  Yes once a match is found it is based truly on Peer 2 Peer networking, but the disconnects are still caused by both matchmaking server issues (still active to record stats of the game) or host disconnects (host of the P2P game session).

Now, in my own experience and that of every PS3 owning friend of mine that has CoD4/5, it is a very laggy and disconnect prone experience.

And finally as I said, this was as of 1 year ago for CoD4 on PSN and 4 months ago for CoD5 on PSN while 360 info is accurate up to this day since I play them a lot.  Maybe something has changed recently to improve the experience. Maybe since the PS3 just has such a small userbase compared to the 360 in the US, perhaps I am just in a "dead zone" where there isn't much activity so it is connecting me to people farther away with slower internet... You never know, but that again goes back to matchmaking systems on the PS3 version not working as well.

COD4 looked and played exactly the same on both HD consoles, so I don't see why the same wouldn't happen for Modern Warfare 2.

However, I'll back up nightsurge's comments about the servers. COD4 Xbox Live servers are better than PSN's (PSN's servers for COD4 aren't THAT bad as some people make it to be, I haven't experienced any serious lag, but there is quite a noticeable difference when compared to Live servers).

Whether this'll be the case with Modern Warfare 2 is beyond me. I hope not, as I'm getting both versions.

While I dislike defending nightsurge, who is so often oh-so-wrong-on-almost-everything (hehe, jk nightsurge... sorta ;) ), consider the following:

A) Matchmaking services are the same on both
B) Game client performance is the same on both
C) CoD4 is not true, serverless P2P -- one client is used as the host (server), and a significant chunk of the lag experienced dependant on that person's connection quality.
D) (this is the important thing to consider) Given (C), and the fact that MS charges $100 for wireless on a X360, which set of gamers (PS3 or X360), ironically, do you suppose tend to have a greater percentage of higher-quality wired connections (as opposed to wireless) to host CoD4 servers with?

Lots of average joe gamers don't understand the difference between wired and wireless, in terms of connection quality, meaning lost and misordered packets, etc. Sad, but true. By the nature of the beast, the X360's server set will probably tend to have a slightly higher average quality than the PSN set, on any peer-hosted service, due to the fact that X360's are natively crippled, with regards to a popular modern convenience (wireless networking).

Dedicated servers (which XBL doesn't have, as far as I know), on the other hand, will always be *vastly* superior, and PSN has a few games with just that, and some more on the way. I think XBL may actually lack the supporting structure for dedicated servers, even, which is why you see so many MMOs going to the PS3/PSN instead.

Because they probaly have a deal with Microsoft and the Xbox 360 version is expected to sell better so they want to add on to it.