3.5 gigs of RAM problem, yet I AM running x64?????

[Guest RyanK]

I have 64 bit vista installed and yet I only see 3.5 gigs of RAM being used

out of my four. I know x64 vista ultimate is designed to use up to 8 gigs of

RAM, so what is the problem? I don't think this had always happened either,

which is strange.