(free) RAM testing programs available on the WEB.
Assuming it passes, then dispose of the existing RAM as desired.
I just upgraded to 2 1-gig sticks of RAM for my Dimension 1501. Not having upgraded RAM before, I'm not sure how long to keep my old 512-meg sticks, before I know that the new RAM is good. the task manager tells me that I have 1.964 megs total, so the system is reading it now--but I'm wondering what kind of a grace period I should give it, before I ebay the two smaller sticks for 10 bucks or so. Is it a matter of, if it works it will work, period? Or should I wait a couple of weeks, or a month, before ebaying the stuff I took out?