installing windows vista/ xp over and over?

hello

so i have windows xp that i've installed 2 times on the same computer, but i also have vista which i've installed 3 times on the same computer. both are OEM. i reinstalled vista 3 times before i got xp. so, i was wondering if i try to install vista again, will it work or will i have to get a new key from microsoft.......

im not dual booting btw

thanks