I recently installed 2gb of DDR2 ram to my computer, and it booted up just fine. But then when i check to see how much RAM is showing, it only finds 2.98gb. Is it because my motherboard only supports that much? I am also using windows XP professional 64 BIT. My motherboard is an Intel D945GCPE.
It sure looks as if you had a 32-bit version...Are you certain you've got XP Professionnal 64-bit ?
If you do, are your modules fully plugged in ? It might not be pushed far enough. Don't hesitate to put some pressure on them, until you here a definitive click.