First you need to start the Registry Editor, by running regedit.
The following is from memory, I'm not on a Windows machine right now to verify.
There are two sets of Run keys in the registry. They are located in both the HKEY Current User, and HKEY Local Machine. Under those go to Software, Microsoft, Windows, Current Version, Run. In the Run folder you'll find the entries for each process which will be started with the machine. Remove the ones you don't wish to have start.
Messing in the Registry without knowing what you're doing will quickly make your machine inoperable, with the only method of repair being to reinstall Windows. That's the caveat of which I spoke.
