If your PC is, shall we say, lacking balls... I'd recommend the PS3.
If your PC is running on rocket fuel, by all means use the PC.
My PC was a custom build from a geek store, but I opted for the econo version. I just wanted the box so I could swap out parts when they die.
I don't like to update drivers and incompatibility issues. With the PS3, you don't have to bother with any of that. It'll run games, period. There are occasions where it'll need a standardized update, you just plug it into the Net and it'll do its magic.
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Heres the basic 'skinny' on the PC vs. PS3 debate..
If you have a commonly available PC that you bought from a store, about a year old and it cost somewhere less than $500, it probably will not play "hot" games.
If you wanted to upgrade that PC to play the hottest new games, it'll probably cost you at least $200, if not more. Dual core, and good graphics card. RAM.
The resident geeks can speak more precisely on this, depending on your make and model specs.
The difference is, a brand new PS3 costs about $250, cut and dried, plug-n-play. No bullshit required.
So, thats where you have to make your personal decisions.
Personally, I thought it was money well spent to get the PS3 console, not only to prevent much anguish in upgrades, but also to prevent many hundreds of hours of hi-stress computing on my PC. I don't want my PC to die, and then I'd be completely "in the dark."