Well I guess you must be lucky, all the techs I've spoken to say it uses 1Gig in full working mode and that seems to be born out by my experience of it and what Agiel's tech peeps are saying too!
I don't know, maybe it depends on which Vista you're using, I'm on Ultimate 64, what are you on?

Injustice will be avenged.
Cofiwch Dryweryn.