eh, no. yes. depends :p
one thing is kernel+system mem usage, that is in my system now at 1020MB
other thing is superfetch.
If you have 2Gigs of mem, vistal itself+apps would use ~1GB and the rest is for superfetch. thus in taskmgr it shows 17MB free mem for me lol.
Vista does use all the mem, but this patch was intended to cut down kernels memory use. but it does still use full mem for superfetch