Xp pro SP2 will not recognize my 3.5 gigs of ram

I have a abit aw8d mobo. The maximum amount of memory is 4gb i have 3.5gb. 2 of the sticks are pc6400 1gb each 1 stick is pc6400 512mb and the last one is pc 5300 1gb. I can see the memory in my bios and i can see the memory in msinfo32.exe but i cannot see the memory in system properties. My question is am i losing resources or is all my memory being used?