TightVNC and original VNC
I have both flavors in my shop and use TightVNC at my workstation to access them. I have never had a problem regardless of what they are running on the other end.
When I need to access computers from home over my cable modem, the best compressionmakes the connection respond with the same speed I get over my LAN (although the picture looks blurry). I can't imagine how I got by before this program. (I'm an IT shop of one and support about 90 users and seven servers.)