I've listed what I put in my Vista build. Keep in mind that the motherboard, processor, and ram are the heart of the system...that's where you want to spend the most. The ones I've suggested work together and run Vista, in all it's glory, extremely well.
Motherboard-ASUS A8N-SLI Premium
A very nice board...very good cooling...very good performance
Processor- AMD Athlon X2
(dual core/64 bit) Runs cool and fast
This is a 2 gig matched pair which has been tested in the ASUS motherboard above...ideal for dual channel use...IMHO, the best ram available for Vista
Video Card-Radeon 9700
Hard drive- Seagate 40GB
CD/DVD- Sony makes some good, affordable optical drives.
Sound Card-The ASUS motherboard above has very adequate integrated sound.
Operating System- Microsoft Vista(currently business edition, but will change to home edition)
Monitor- White Gateway one <---Get an LCD widescreen...