The 3.0Ghz one won't necessarily run hotter. There won't be a big differentce in temp at all, if any. If you can afford to get the 3.0Ghz get that, as it's more future proof cause ut's faster. But the 2.8Ghz will more than suffice. I presume you are getting the 800fsb models. You will probably not notice a significant difference, but there will be a small difference in performance. So would get the 3.0Ghz and plenty of high speed RAM for excellent of performance.