The downside to the high-end PC stuff is that your PC is outdated very quickly compared to console titles. With consoles, developers have one standard of hardware to work with. With PCs, new hardware is released every 6-8 months that trumps the previous models, giving the developers more to work with.
Of course, it helps that the developers actually know what they're doing. For example, Company of Heroes runs pretty good on my 2.2GHz Athlon64 cpu and NVIDIA GeForce 6800 GT 256MB card. Supreme Commander runs like shit. They were too ambitious developing that game. Oblivion runs great on my 360 but like shit on my PC. In fact, there aren't many PCs that can run Oblivion well.
It's also a huge headache if you get into optimizing performance via video settings in games. It's a lot of, ok tweak this shadow setting once, now load, now play, now go back, tweak lighting or shadow, now load, now play, etc etc. It sucks.
But again, there are lots of great titles on the PC that don't come to consoles. It's not totally worthless to stay out of PC gaming, but just know that if you spend $1,500 on a gaming PC, that it'll drop to $700 worth in six months, and you'll probably get 2 years of high end visuals out of it before you have to start really lowering settings.
