I agree with Yams and Face's general postings.

For CPU, get a Core2 Duo. I like AMD, but if you look at the prices and performance, AMD only has a better price/performance ratio in the lowest speed dual core chips. If you buy anything faster than the base level, buy a Core 2.

As for power supplies, I used to use Antec power supplies (a lot of them), but recently their quality control has decreased significantly and they are not worth getting now. I highly recommend many of the CoolerMaster and Corsair power supplies. (Unless you are running SLi or a huge RAID/JBOD of harddrives, you don't need any thing larger than about 400W)

As for Vista, I've been using it for 8 months now (beta and the release versions through our MSDN subscription at work), and it is definitely not worth using yet. It is more headache than benefit and XP Pro is still a valid alternative. Stick with 32-bit, especially if you are getting less than 4GB of RAM.

For Graphics, instead of a 7300 (which is slow), at least go for a 7600GS which offers a great price/performance ratio for its price bracket.

Best of luck with this computer build.