I'd like to suggest Dameware Mini Remote Control.
Since the time that I knew it, I always suggest it to the company that I work.
It relies to somekind of RDP protocol, but sharing the screen, so you'll have the speed of RDP with features of VNC (even more, like be able to enter logins in UAC warnings and remote install).
Great piece of software.
Please, pay atention that there's the Dameware Remote Support. It's more expensive...
The cool thing that you can do is, when you're on an computer asset page, you can start it with command link to connect to that computer (as soon you create a link to it), so you don't need to deal with computer list update.
In fact that is an feature that I always ask them, but they're not able to attend.
I even did a small app running in tray area, monitoring network logins, building a live user list. 🙂
