DDR2 not registering correct value

Guys pls help me on this one. My mobo is a gigabyte GA-X48-DQ6 and I put a 4gb DDR2 Corsair XMS2 memory. Now the problem is this, when I check my windows XP system info it only showed there that my RAM is only 2.75gb Why is that? Is there anymore software out there that is free, where I can use to find out the real score? Pls guys help, Im new in this stuff. And I work so hard to invest on my hardware, that I feel I bought a wrong or defective DDR2. I'll give you more details just ask away.

Unfortunately Windows XP 32bit can only detect about 3GB of memory maximum. Upgrading to Windows XP 64bit will allow you to have more than 3 GB. Your hardware is fine, you just need to up your OS.

It's a well documented issue, even the forums has a couple of threads on the subject. Search for 32 bit & 4GB, you'll get quite a few hits. In the end the only answer is to do what Whiffen says, upgrade to a 64-bit operating system if you system supports it.

Wow man!!!! Great help guys!!!! Finally I know the problem!!! MY eyes hurt and my head, coz of all the research Im doing. Now I can sleep peacefully. Mystery solved! Tnx to Whiffen and Didou!!!