If I WAS to....

[quadboi]

I have 1gb ram at the moment Pc3200 (Crucial) ...2x512mb


If I was to buy JUST 1 stick of pc3200 Crucial ram, and put it in the 3rd slot would it be fine? Or do I need another 2x512mb

 

[dale1uk]

It would work but not in dual channel, and would also run at 2t not 1t which you you see a performance hit from.
Best bet, but possibly not the cheapest, is to sell the 1gig you've got and put the money towards getting a 2gig (2x1gig) kit