*Is necessary to have ultimate version for 64 bits?

*No, it's not necessary to have ultimate!

Ultimate gives enhanced security features like the "Bitlocker drive encryption" which I wanted!

Vista Home 64 would do just as well if you don't need the enhancements of Ultimate, of course you could always go XP64 but as things are moving to Vista I'd go with that!

Don't believe all the horror stories you might have read about Vista, there are a few odd things going on but on the whole I don't find it that bad!

Injustice will be avenged.
Cofiwch Dryweryn.