id just dual boot the two of the OS's, vista is a RIP-OFF GIMICK!
Microsoft just do not want to spend some money finishing off the whole OS, so they just made a few graphical updates to windows XP, and then managed to spoil the WIN32 original concepts!
And then they have the cheek to sell it for such an huge amount of money!
If u just want a sexy OS id dual boot XP (XP becoz it can run every app in the world, and is a lot better than linux in my opinion) and a linux distro like openSUSE or Ubuntu 7.04.(linux coz it can run beryl and is very easily themeable)
by the way windows is only insecure and unstable sometimes because of the amount of people who use windows, not because it is rubbish!!
The more people using something, the more problems you have got to expect!
linux is actually quite insecure if you are not an advanced user!
linux is actually slower than windows because if you take all of the rubbish out of windows, so that it is as bloated as linux you wil notice windows is faster!