Why won't my comp read the extra RAM?

Hi,

I've taken out my 2 old 1gb RAM sticks and replaced them with two 2gb ones, meaning I should have 4gb's RAM.

But my pc is only reading up to 3007mb's RAM, instead of the 4096mb's.

Any help would be appreciated.

My PC specs are as followed:

XP Professional SP3 32 bit

Palit 9800GT 1gb

Intel DuoCore E4500 @ 2.21 GHz

Thanks for the reply,

but how much would upgrading cost, roughly?

All it takes to upgrade is a 64bit version of windows, these retail at the same price as 32bit versions so it depends on the version of windows you want, i'ld say about $70 is resnoblemarkop2003

Ok, thanks man.