VNC stands for Virtual Network Computing. Originally developed by AT&T in conjunction with Olivetti Research Labs. Development forked and you can now find the latest version at http://www.realvnc.com/.

VNC allows you to take control of a remote PC in much the same way as NetSupport or pcAnywhere does. The biggest difference is that it's free - the software is open source. It's also cross platform, a lot more than either of the two alternatives presented here.

I have used VNC extensively, both over a LAN and also over a dial up connection to support remote machines. It works well, I like it a lot.

Also see: NetSupport, pcAnywhere