Run restricted programmes from guest a/c

You can run a program as a different user without logging out and back in again. Right click the icon of the Program, select Run As...... and enter the user name and password you want to use. This only applies for that run. The trick is particularly useful if you need to have administrative permissions to install a program in domain controlled network, which may require. 

BEWARE :Note that you can have some fun by running programs multiple times on the same system as different users, but this can have unforeseen effects.

Speedy Network Browsing

Windows 2000 & XP machines delay as long as 30 seconds when you try to view shared files across a network because Windows is using the extra time to search the remote computer for any Scheduled Tasks. Here's how to prevent this remote search for Scheduled Tasks:
Open up the Registry  with  Start Menu -> Run-> regedit and go to :

HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Explorer/RemoteComputer/NameSpace

Under that branch, select the key :

{D6277990-4C6A-11CF-8D87-00AA0060F5BF}

and delete it.

If you like you may want to export the exact branch so that you can restore the key if necessary. 
This fix is so effective that it doesn't require a reboot and you can almost immediately determine yourself how much it speeds up your browsing processes.