http://www.showmypc.com/
Great for remote troubleshooting and it's free. End-User simply downloads "
Show My PC to Remote User v3010 
" and shares the created password with the person troubleshooting remotely. The trouble-shooter then can grab control of the end-users machine to help with installations, driver support, or to show how to use a program.
Very powerful tool that we are using at work.