what should i dual boot

[Oscar1613]

i just built a new computer ( x2 6000+, 4gb ram, ati xt1950xt ) so i installed vista ultimate x64. i want to install a backup OS in case any programs, games, or drivers have any issues with vista x64, but i'm not sure how far back to go. if something has an issue with vista x64, is it likely to have an issue with xp pro x64 as well? in other words, should i install xp x64 as my backup or go back to regular 32bit xp pro?

 

[Cutthroat]

Go with XP Pro 32bit for compatibility, XP64 has it's share of troubles with compatibility too.