yes. but when you switch, does it make your now-active window run smoother? this should be the case.

also, do you have your ram set up optimally? you now have three so im guessing you were using four 1 gig ram sticks. could be problem with ram controller so put your ram in these banks: bank 0, bank 1 and bank 2. leave last bank empty.
usually mobos are set up this way.
ram controller 1 is connected to ram bank 0 and 2.
ram controller 2 is connected to ram bank 1 and 3.

best to do would be to get a matching ram stick for your last bank. try it and see if that fixes your problem.