RAM Problem

Hi guys, first of all heres the specs for my old machine

Aopen AX4R Plus Mobo
Intel Pentium 4 3.0ghz
2x256mb pc2700 RAM I have 4 RAM slots
OS Windows 7 build 7127
so
I'm just one of those people whos testing windows 7 on an old machine but I thought of buying another 512mb pc2100 RAM (my mistake)
Installed it and worked but the problem is the bios itself only uses 768 MB of RAM!

when I get to my computer properties it says 1gb RAM(768 Usable)

does anyone have any idea why its not using all of the RAM O.O!

Seems like you chose the correct memory to upgrade with for your motherboard. Also, the board has a max ram of 4096 MB, so you're good there too.

Perhaps a bios update will help, if one is available.

I see O.O; flashing bios is just too scary =/