Need opinions: What's the best software to manage/troubleshoot computers located at a remote location?

I've seen other administrators run a program where they log on to a remote computer across a network (or even the internet) and essentially take control of the remote computer, with the ability to Move the mouse cursor, open/close programs, run scans, etc... on the slaved computer. Is this some sort of "spy" software they they can also use to spy on the users...Well they spying part is kind of off the subject but:

I could use really this ability to help manage the computers at some remote locations...Would PC Anywhere, Carbon Copy, or some other software installed on my computer provide me with this capability? Or are there other applications that might do this better? Its a real pain to try to describe to novice users at a remote locations how to resolve a problem over the phone (especially when I'm such a novice myself)...And its an even bigger pain to get in the car and drive several hours to try to fix what should have been a minor problem... I'd love to have the ability to pull up their computer screen remotely so that I can see exactly what they see on their computer screen, and then even be able to troubleshoot and/or resolve the problem for them remotely.

Does anybody know what the best software apps for doing this type of activity are? Are they expensive?

HELP!

Scott Evil