Well yea, when I dual log an MoG it somehow finds a gig of ram to use. and when I log off the game it'll be at 950-1000mb, though only for a while, then it goes back to about 800 or so.
It seems that XP prioritizes where ram goes.
Also when I only had 512mb my system only used about 50- 80mb. for some reason when I upgraded to 1024mb it used more at idle. cept under full load.