My computer is about 4 years old has anan AMD Athlon processor, motherboard GA 71XE4 AMD 750 AGP set( This is what it says on the manual. 128 Megab of RAM I run on windows 98 SE and started getting message saying insufficient memory. I ran some online tests thro' Pitstop and their advice as well as advice from others waas that the best way was to increase the memory. A friend said it was easy to put it extra memory and she would do it for me. We therefore went off with the manual and purchased 2 256 Meg strips,they looked different from the original, put them in at which point the computer wouldn't work at all. We took the strips out as well as the original and went back to the shop. They said it should have worked but the strips they gave us were pc133 and the original was pc 100 so they advised us to try and get the pc100. This we managed to do and I bought again 2 256meg strips which looked identical to the original i.e thay had 16 chips , 8 on each side.The brand was Matrix. We then inserted the 128 in its original slot and the 2 256 along side so a total of 640 meg. The computer worked sort of but was not happy. Furhter advice suggested increasing the Maxfile cache, this made no difference and also I was then told on all sides that windows 98 doesn't like more than 512 meg. No problem. We take out the 128 original stick and put in the 2 256 meg in slots 1 & 2. The computer started to boot up but then had conniptions, loads of error messages , missing Dll files and heaven knows what, impossible to do anything. Thought perhaps it's essential to have the original stick in place so put it back in slot one and added 1 256 meg stick, this time it booted up ok but as soon as I tried to get on to the internet lots of error messages, impossible to carry on, so now I'm back with my original 128 meg SDRAM and 2 very expesive 256 meg strips sitting on my desk. Does anyone outhere understand what any of this means and what I can do about it?