Built my system in 2002. Last major update I did was to the video card, a 100$ investment, last year. Newest game I bought would have been civ 4. (actually, is was C&C: the first decade, but since thats just all the old c&c games remade to run on xp, I don't count that as a newer game) I seem to run unreal 2k4, swat 4, or gal civ 2 just fine as well. Plays those flawlessly on thier normal settings.
As reference point:
P4, 2.4 ghz (not dual core, not 64 bit, just plain old p4)
1 gig ram
running XP
ATI Radeon X1300 series vid card
Granted, I don't know how old your system is. But mine, as its approaching 5 years old now, still runs new games just fine.
Monetary wise, I guess I've invested probably $1500 usd in it over its lifespan so far. But things like the 22 inch monitor, dual plextor dvd burner, multiple hard drives set up in a raid 5 architechture, high end Audigy Soundblaster sound card with 7.1 speaker system, etc, do tend to up the price as compared to a console, which has no need for any of that stuff.
I'm not saying that consoles aren't nice. I was simply giving counter point to Loto's comments.

Edit: now if I tried to run PS on my pentium pro machine built back in '95, then yeah, no matter how much tweaking is done, it still wouldn't run it. But like wise, a SNES ain't anywhere near powerful enough to run a Wii game, even if the game did fit into the SNES cartridge slot.