software to remotely control another machine?

I'm trying to figure out the best software to allow me to control my mother's pc from a distance. She periodically needs help maintaining her machine and I've thought of using PC anywhere or vnc viewer to do that. Does anyone have recommendations as to the best tool for this? Thanks.

For purposes similar to what you describe, I am happy with the free version of Logmein.
https://secure.logmein.com/US/home.aspx

I assist about a dozen elderly or otherwise timid computer users.
All of them are in my My Computer's group at my Logmein Account.
I never access their machines unless asked to do so.

I've been using Logmein in this way for about 3 years with great success and no cost/no hassle.

Thanks, this looks exactly like what I'm looking for. I'll give it a try.

Should you want another one to compare, TeamViewer is what I use, easiest most friendly one I have found.