you really shouldn't think too much about performance but should just think about another used computer as backup. I saw some recertified Compaque computer for about $100 at Ubid.
I currently have a Dell Optiplex GX620 with an Intel Pentium 4 3.00GHz and 2.00GB and a 149GB HDD. I need it to be as fast, but faster than this one for college to run side by side in case this one looses connection or I have to open other windows. Can you advise what am I looking for is it in the general specs or brand name I am looking for. Am I to be concerned with the processor speed, hard drive size, memory or a combination of all three. I have about $100 to buy another used PC only, I have the other monitor and accessories to go with any help would be appreciated.