Even though XP is okay, I still prefer Windows 2000 Professional.
The easiest way might be to download Startup Control Panel. I have never used it, but it looks like it might do what you need. It also saves you messing about in the registry, however .....
If you don't mind messing with the registry you can try the following procedure to manually remove entries:
Start Run Type: regedit and then hit enter. Go to (you navigate just like file directories) HKEY_LOCAL_MACHINE Software Microsoft Windows CurrentVersion Run (or RunOnce, OneOnceEx, RunServices, RunServicesX, RunX) [Programs may appear under one of these keys. If you have unchecked them they should not appear under Run, RunOnce or RunServices]
Backup the existing values.
Click on the "run" (or "RunOnce" etc.) file icon and choose Registry, then Export Registry File. You will see a file save box. Click Selected Branch under the Export Range area. Choose a location and name for your backup file and click Save.
For each key ("Run" and RunOnce" etc.) you should see a list of programs the same as those under the msconfig startup tab in the right-hand pane. Right-click on the programs you do not need anymore and choose "Delete".
Of course, you only need backup branches if you are changing them.
Changing registry values can cause serious problems. It is possible that deleting or changing a wrong value could mean that your machine will not restart.
evilCTM accepts no liability for the use of the information above
If you are not comfortable changing the registry then just try the software I listed. While the procedure outlined above should be safe there is a small chance that one of the entries you delete could cause problems. However, if you are certain that the program is no longer needed and has already been disabled (in msconfig) then removing the entries should be OK.