I'll second the Intel Q6600. It runs at 2.4GHz default but on water cooling it can easily clock to 4GHz+. Mine is at 3.2GHz on the air cooler that it comes with. And it's pretty cheap as well.

Also make doubly sure that Vista32 will run all 4GB of RAM. AFAIK, it does the same thing as XP, ie it will only let one app use 3GB at most. For 4GB, you need the 64 bit version (in which case you may as well get XP 64, which is a lot better)

The rest of your specs are fine IMO...