pc problems

Hi. I have two problems I hope someone can help me with. I have a Dell Dimension 2400, 2.4gig Celeron, 1gig ram, XP Home

   The first one is more of an annoyance. Last year I installed a tuneup utility. It included it's own System Restore program which took over from Window's System Restore. It didn't seem necessary so I uninstalled it. After uninstalling it, the only way I could  access Windows System Restore was through Safe Mode. I figured it must have broken some link in my OS or there must be a part of the utility's program that did not get uninstalled. A couple months later I put in a new harddrive and did a clean install of my OS. I still have the same problem. Could my BIOS be corrupted, and how hard is it to reinstall a BIOS?  I read somewhere that this should only be attempted by someone who knows EXACTLY what they are doing NOT by someone who has just an idea of what they are doing.

   The second one is a real pain. It seems some programs or applications will not load into RAM. For example my screensavers start okay then after a couple of seconds the harddrive starts clicking, the harddrive light starts flickering and the screensaver runs choppy. I have very few programs running in the background, and my Task Manager shows that I have about 600megs of RAM free. Could it be that my RAM stick is faulty and will not load to capacity? If this is so how is it that the computer recognizes the 1gig RAM stick? Or could this be related to my first problem?  Thanks in advance for your help.