Ok thanks guys. Basically the reason I asked was cos when I bought my laptop around this time 2007 from ebuyer, they advertised an offer for Kingston 1GB ValueRAM when bought with, and the laptop already had one gig of RAM inside it, so I thought I'd get it and upgrade to two. Only I didn't realise that the 1gig inside was made up of 2x512MB modules, but I'd been told it would be fine to mix the sizes anyway. I've forever hated my laptop, often hanging which I blamed on Vista being rather process heavy, but today I opened it up to check what RAM I had, thinking I might get some more RAM and hope it solves the problems, and then I wrote down the model numbers of the RAMs and googled them, and I think I found out that the 1gig ValueRAM I bought runs at 533MHz whereas the original 512MB RAM in the laptop seems to be 667MHz according to tinternets, and I'm thinking it's a possibility this may be an explanation to all my problems. I've found some matching Kingston ValueRAM, and I'm gonna get a 2GB stick to mix with the 1GB stick, this'll all be fine, right? The model number of the RAMs are exactly the same except with 1G/2G at the end.