memtest86 sounds like a good idea. I usually let the program run overnight so that by the time it's morning, it would ran at 10+ passes already.
If the test comes out as negative (it passed all of them), I would just remove ALL add-in pci, usb, serial, parallel, etc...from the motherboard/pc. Just leave your video card in. I once had to install Windows XP with an old Voodoo3 PCI card, and it would freeze every time at about 35% into the installation. Replacing the video card with a 9MB AGP worked perfectly fine. It might be an adventure.
OPTIONAL: If you want, you may also disable ON BOARD Lan, audio codec, serial controller, parallel controller, USB controllers, floppy controller, SATA (if current drive is not SATA), etc in the BIOS. Re-enable them after a successful boot-up one by one (or all at once with fingers crossed). The purpose of this is to make sure whatever drivers Vista is using (that we can control) isn't causing the BSOD. Even more of an adventure!
Cliff note:
1. Memtest86
2. If fails, try a known good RAM
3. If passes, remove all connected components from mobo (pci,usb,etc...)
4. Reinstall Vista
5. If still BSOD, try exchange video card
6. Reinstall Vista
7. If still BSOD, try the optional
8. If still BSOD, ???