Haha, I just "upgraded" to a 6600GT video card (it was ~US$200, and the rest of my system will hold anything better back). That's a long way from the 7800... but at least I can now buy and play Battlefield 2.
I spent some (a lot) of time reading this site's reviews recently - they seem as good or better at reviewing than any of the other 10 million hardware reviewers out there:
http://www.firingsquad.com/hardware/
This one looks particularly relevant.
They also have a really cool section of guides (more or less just written) about building a high end gaming, workstation, and hometheatre pc.
http://www.firingsquad.com/guides/
Their
ultimate gaming pc.
I've been playing with linux instead (Ubuntu) - I must have burned 10 hours getting the friggin USB wireless adaptor to work on my WPA secured network at home (could do it again in 15 mins now though...).