Choosing slots in MDD?

[prymsnap]

I plan on re-seating the existing memory in a MDD to see if I can solve some performance issues (cursor freezes and crashes). There are four slots available, and the tower has two 1 gig sticks.

Should I also try putting the two sticks in the unused slots instead of the ones they're currently in? Or do the slots need to be occupied in a particular order?

Thanks.