mixing rd ram

hey i'm a newby with some crappy gateway computer with 2 64mb rambus ram sticks and i was wondering if i could install 2 more 128mb ram sticks of a different brand with out experiencing any problems because i heard you shouldn't mix ram sticks

Each pair has to be the same. Another pair might work ok... but then again it might not. Even if the 4 don't play well together, at worse, you should be able to use the pair of 128 RAM by itself which would double what you currently have.