I need computer tech help!!!?

My 2003 Sony Vaio XP Home desktop (w/a 500G WD ext. Hard Drive) is running out of memory---11% left---even though I put most apps and photos on the ext. drive. It has been dropping for quite awhile, and I read to check the Virtual Memory usage in Task Manager for the biggest usage. That is apx. 150, 000 for IE with my name as the user, followed by 2 ccsvchst.exe's with the first as SYSTEM, and the 2nd as me as the user. I believe the last 2 are Norton? They run 40,000 and 28,000 respectively. I've used Glary Utilities to clean up and have removed several programs. It's as if I don't have an external Hard Drive, almost like everything is going onto the C: drive, but it's not showing anyplace but the external G: drive. Is there any way to find the problem, or is it that my PC is just worn out or what? Thanks for any help.