[Dimension 4700] Erratic mouse movement problem

Hey all,

I've been having problems with my Dell mice every time I use them on this desktop; I'm not sure if it's the mice or the computer, though I don't remember the pointer movement being so erratic before I got a replacement hard drive [my other one kind of... died XD]. The pointer will just blitz off into a random direction or kind of stick in one spot when I'm sure I haven't done any wierd movements or lifted the mouse off the mousepad. The mice are both generic black and gray optical dell mice, and they work okay on my non-dell laptop as far as I can tell, not sure if I need to upgrade drivers for them or something? o.O If I do, can someone point me to the right link? [I swear, the Dell site has had so many re-arrangements that it's just plain confusing! Not to mention the lack of support for the .ca side x.x] Or if this is mouse problem, I'll have to find myself a non-Dell mouse to use [oh the irony ;>>]

Thanks,

~Jessicat715