VNC works fine, been using it in our labs for as long as i can remember
Remote desktop however..
1 as Brian says it ll close the session if you disconnect
2 Messes up the the host resolution, color count ... and therefore may very well affect your tests ( bitmap comparison, coordinate references.. )
It's kind of funny, but I have heard of people using multiple levels of Remote Desktop to get it to work. So they had 3 machines, 1 that the automation is running on, an in-between machine that you have Remote Desktop connected to the automation machine, and a 3rd machine they were actually working on to remote into the "in-between" machine. That way, they could always leave the Remote Desktop session running and maximized on the "in-between" machine and close it down on their own (3rd) machine.
Seems like a total hassle to me. Either use something free like VNC, or our company uses some other remote product called NetOp that isn't great, but works better then Remote Desktop when it comes to SilkTest and running automation.
Leave the machine running, and let SilkTest connect via tcpip to the agent process on the target machine. This allows you to execute and still have control over your keyboard...and yes, I use remote desktop all the time executing scripts still...saves me having to toggle my monitors (which I hate doing)...I just leave the remote desktop instances minimized.