All righty...
Some choices for a single video card on a decent budget:
- 8800 GTS (G92) 512MB. It will be released on Dec 11, apparently, and should be under $400 unless demand overwhelms supply again like they did with the 8800GT.
- HD3870. Also excellent value for money. Less speed but less money too.
- overclocked 8800 GTX. For example my 8800 GTX OC2 can still beat the new 8800 GTS G92 in some benchmarks. Not by enough to justify $100 or $200 more IMO, and it consumes more.
- wait for GeForce 9 cards. This is risky, because we have no clue if they really will show up in February, how much they will cost, how good they will be, if the drivers will be any good right away or only 9 months later, etc.
Choices of CPU: Phenom seems to be a bit slower than the Q6600, at the same clock. Also, Phenom is sold at 2.2 GHz and doesn't overclock much, while Q6600 is sold at 2.4 GHz and overclocks nicely. If you like AMD and want to give them a hand in these horrible times, and you're not going to overclock anyway, go ahead and get a Phenom, sure. You'll get a bit less CPU performance but it probably won't hurt because most games are limited by the graphics card or hard disk anyway. That is, you will often get the same fps whether you get the Phenom or the Q6600. For things like encoding video your hard disk will bottleneck the system. For example my Q6600 is at stock and never manages to reach over 81% usage. With a 2.2 GHz Phenom I would get the work done in exactly the same time as with the Q6600.
If you get 4GB of DDR2-800 you'll be fine for a couple of years. Don't waste your money on DDR3.
The GeForce 10 series should appear 4 quarters after GeForce 9. nVidia promised to have a new high-end card around every Christmas.
Motherboard: for Q6600 I like GA-P35-DS3R or aBit IP35 Pro. For AMD I'm clueless, but I'm sure somebody here can recommend something good.
Get a good PSU. My favourite is the PC Power & Cooling Silencer. There's a 610W version, which should be enough for a single video card unless you wait for GeForce 9 and nVidia did something fantastic there. There's also a 750W version (which I got for myself just in case I want to try SLI later).