This is probably a dumb question, but what the heck, here goes. Can someone explain to me the significance of having a 8mb cache on a hard drive, say as opposed to 2mb cache? I know that it's obvious that 8mb's going to perform better. But I guess I just don't understand what function of cache is on a hard drive. Can someone enlighten me? I'm thinking about buying one of those 80mb SE Western Digital hard drives, I'd like to understand just what I'm buying.