I also have both systems, and honestly the difference is negligible. Some games seem darker on my PS3 than my XBox, but as far as performance and handling; they're really about the same.
Gaming technology changes (even still) once a year. It USED to change every 6 months or less. I recently bought a new 4870 X2, and ya know what?: It looks the same as it does on my kids system with an older X1950. This game is very versatile and runs great on a variety of systems.
I do wish some game companies would release their demos earlier than game's actual release date like they used to. That way, you can actually see (hands on) if your computer can run the games BEFORE they come out. Sometimes, you can look at all the #'s in the world, but unless you actually load it up, you don't know for sure. I see a lot of "Will my computer run this game?" questions, and the reality is - Download the Demo and play it. If it runs on some arrangement of settings and it's acceptable to YOU (not the 500 other gamers with gaming rigs), then buy and enjoy.
3.8GHz Extreme (non-duel core), 2GB Kingston PC2-5400, 2 WD 250GB (RAID 0), WinXP Pro (32-Bit), ATI Radeon 1950XTX (512MB), SB Audigy 2 ZS, 19" Samsung SyncMaster 931B (DVI) An "older" system - I've had ZERO problems with this game. Installed no problem. No problems with sound or video with everything maxed at 1280x1024. I noticed a bit of a sound loop a couple to times throughout the game, and loading between 'levels' was a little slow with a 5 second hiccup in video after the load. Other than that, mid-game and mid-fight; I've had no problems.
TheCyberKnight's comments