I tried putting the /PAE switch in the boot.ini file to no avail. I don't want to upgrade to win64 because it won't run my apps.I want my OS to acknowledge the memory I put in my computer. This problem is heavily discussed everywhere, and the /PAE switch should have cleared things up.What do I do, and how do I do it?do I do I doooooo.......Anyway, I have a copy of Sabyon, but I can't use that for college. I'm tired of the system crashing when it finds that extra GB of memory, and I was hoping that someone would have a answer, or a link, or both! An answer which is clear, comprehensible, and will assist me in making my computer realize that it is wasting one gig of potential.Please help, with your ability to look at this from a different angle, and my need for an answer; we can make this story have a happy ending.Thank you for your time in reading this, I hope that someone might have an answer for me, and that someone will be my hero ^_^I've tried every acceptable solution to this problem and it's still not showing me what I want to see.Thank you all for your searching efforts. I can't figure out the root of this problem. I turned off my page file; as was suggested on a Cnet forum, and it started acting like it only had 2.9GB to work with. My frustration is a deep gulf, and my apprehension like a tender bruise on my ankel. This thing, this 'XP pro' seems to want to force me to change my OS, or install the 64bit edition, which is buggy and doesn't support any of my applications. Then there is Vista, and I know better then that. There is no problem with the physical memory, I've had the BIOS test it extensively, the finger can be pointed squarely at Windows. I'm confused how other people managed to get it to read at 3.5GB of memory used, I think it might be that smaller RAM chips were used.It just seems stupid to make an OS with the limitation of memory, but It's also a great way to sell the new stuff...