my girlfriend just got a dell gx150 desktop to use for uni, it only has 128mb ram in it and i want to upgrad it to 512 mb to make it run ok as it is rather slow with just 128mb ram in it. i tryed to use 2 sticks of 256 mb ram in it but it started to make parts on the screen go pixel and i was told it was because the ram was not compatiable. so i have downloaded cpu-z to get th info of pc. it says it has in it 128 mb sdram at frequncy 133.1 mhz. any info on the type of sdram to get and the best amount as iam not sure if 512 is the best amount or if 1mb would be too much.