Devilmaster, writing above was right on but I think there are a couple of things he didn't stress enough. Some companies, Compaq and Mac are the worst, either make their machines so hard to work on or make the parts so hard to get that one is forced to use their service departments. OEM is unquestionable superior. That said, places like Dell and Gateway are hungry enough that they would likely try hard to give you what you want at a good price. The trick is deciding what you want. If there are dollars left over, more and faster memory never hurt anyone.