hello

Well im a gamer and I have to say I would rip out that CPU and chuck a quad core in there, you could pick one up on ebay cheaply enough.
bin the 8800GT, get an ATI, nvidia are usually overpriced and over rated, the new ATI 5850 is acracking card and can handle anything, and is way better value for the money than a 460 or 560.
you could pick up a cpu off ebay as I said for £70, buy new gfx for £150, sell your old parts on ebay and hopefully pull back in £40-50.
dual cores are ok...ish, but for gaming you really need a quad core now, the latest games perform a hell of a lot better with that.