Your PC is much more powerful then a PS3....
and in five years time your PC will still be more powerful then a PS3
One of the only sensible posts in this thread, right now a 260gtx can EASILY play a game in higher res and higher settings than a PS3, this will continue in 5 years, even if new game is far to hard for teh 260gtx to run on max settings, even if you drop down to medium settings and no post processing, the PS3 will STILL be using LOWER options, so will run the same game at a lower rest/lower speed or lower settings.
YOu need a quad core now? tosh, barely any games require a quad core, infact no game out won't run on a dual core not a single one, some games are faster on a quad, that doesn't mean unplayable without, likewise most games aren't any faster with a quad.
In 5 years you'll probably be on dx12, but dx12 will be backwards compatible with everything down to DX10. Infact newer games on PC in 5 years WON'T be backwards compatible with DX9, so anything behind a 8800/2900xt wouldn't be viable in 5 years, anything dx10 and up will still be supported in 5 years, without dx9 and with companies having moved away from it in 5 years you'll unlikely even see the best games released on the PS3 anymore, just the PS4. Unlike the PS2/PS3, games likely won't be as compatible on PS4/PS3, so you won't get releases on both at some point in the future.
There is no question your PC will play games significantly better in 5 years than a PS3, and theres certainly a question if major releases in 5 years even make it onto the PS3, they will almost certainly be compatible with the 260GTX.
a PS3 has only a little more power than a 7900gt, its outclassed by a 8800, let alone a 260gtx.