I use LogMeIn free and teamviewer. With all remote support tools, you have to get the user on the remote PC to activate/setup the remote connection, and in this area Teamviewer is faster and easier. Like Logmein it plays well with Windows Vista and 7's User Account Control, and like Logmein you can do Windows -> Mac remote control and the reverse. Unlike LogmeIn Free, Teamviewer enables file transfers (with low overhead). Finally neither require any router/port forwarding configuration, building a custom executable, etc. Remember one of the most important criteria for a remote support tool is ease of setup for the person being helped.