Check my thread - i have the same problem: Dualview problem with 4:3 + wide
Some solutions at the end, might try them before you decide to buy vista.

I run vista at work and well, i'm not that satisfied. I still regularly crashes. It looks good but all that fancy shmancy is just slowing down your system imho.
If i had vista i'd probably tweek the looks so it would look like XP.
Then again I'm an XP fanboy. I know I'll have to make the switch someday but I'm postponing that as much as possible