RealVNC is the best program I've ever used for remote admin duties! Try it out, you can't lose and it's free...

Nothing's better than that
HTH,
David
[EDIT]
Forgot to mention that it's also cross platform. Mac, Unix, Linux, Windows, Sun, Cisco, you name it they've got it. So you won't have to worry about compatibility issues. And, you can assign display numbers to each computer that you want to monitor. That way, you can be at another location, and still monitor hundreds of computers, all using one destination IP, it would be like 65.66.132.45
:0, 65.66.132.45
:1, 65.66.132.45
:2, etc.
[/EDIT]