Sorry to hear of your Vista problems, which surprise me somewhat !
I too did a lot of teeth gnashing and desk thumping in the 1st days of installing Vista, mainly because of the lack of 64 bit driver availability, and terrible difficulty of finding a modem which had x64 capabilities, and MS/ATi joint decision not to provide TV support for my brand-new ATi AIW card.
Once I finally managed to get my legacy apps to work (with some invaluable help from this forum), and bought a new Vista compatible dual digital TV tuner, I've been so pleased with Vista, I almost never have cause to revert to my XP secondary boot.
Vista has never crashed on me in 15 months.
Are you sure you don't have hardware problems (poor connections, inadequate CPU cooling etc, which are causing your crashes ?)
Have you thought of giving your partner XP back with a dual-boot ?
That's what we do here if you need help or advice.
That way you'd see whether it's your Vista install or the PC in general that's unstable.
Good luck anyway, whatever you decide.