Okay, since you already have 2GB.. Are they both 1GB sticks? And, since you're looking for desktop memory, the real quality RAM will be a little more pricey, so, definitely look around. You could probably get two 2GB sticks possibly cheaper than one 4GB stick. I'm not sure, it just involves looking around at the RAM that suits your setup best. And is this a custom built or pre-manufactured PC?