Optiplex GX60

I have a Dell model as stated. It's all I can afford at the moment, I understand it is an outdated model. It had it's factory 128mb ram. I purchased kingston pc2700, as it was said to be compatible with pc2100, which is what the label on the original ram stick said it was. However, it was not recognized in conjunction with the 128 stick, and alone ony made the computer beep. I have since purchased two pc2700 512 sticks with no luck. A friend had some leftover sticks,  which he let me use to see if they would work. He had two 512 sticks that worked, but created lines across the screen and froze (the sticks were discarded as dead). However, he had another 512pc2700 and also a 512 pc3200. When using them individually, they do not work, but with the 3200 in bank 2 (farthest from cpu) and pc2700 in bank 1, the computer boots normally. However, the computer only sees 3200, and acts like the pc2700 doesn't exist, but will not run without the pc2700. so i figured maybe it could only use pc2100 or pc3200, so i purchased a 1gb pc3200 stick, which the computer will not boot with, alone or with other ram sticks. Is there something that I am missing? Thanks, Brittany.