>>4
Oh, and I forgot: overclocking may hurt your system reliability (and if the system hangs you may lose data or screw things up).
The best way to gain speed (far more than usual overclocking) is by following these tips:
1. Use Windows 2000
2. Don't install bloatware. Example of bloatware: .NET stuff (like ATI's Catalyst Control Center; the classic Control Center is better), Java stuff (like Azureus; BitComet is better).
3. Don't install resident shit. The system tray sucks. No, that icon is not kewl there. Get rid of it.
4. Don't have a resident antivirus. Run it manually on anything you download or are passed in CDs and diskettes.
5. Browser toolbars are not kewl. Get rid of them.
6. Unload services and stuff you aren't using. This step may require some knowledge.
7. Configure your system properly. This step may require some knowledge.