i use vista Ultimate and didnt had any probs with mohaa.
it's over a year now and never had to reinstall or format it.
but a tip for you Cuzo.....
is did you let vista check for updates...........normaly every vista,if it's basic,premium or ultimate does have an introduction center.
there you'll find it for update's.
if thats not the case i'll would check for online help.
ps let me now if it works or not,i will help you.
like hanni knows xp i'll know vista lol.