UltraVNC

For a while now, I have used the built-in Remote Desktop functionality in Windows XP and Windows 7. It works well, but I recently came across a limitation. It turns out that when you log in via Remote Desktop, Windows uses a custom “remote desktop” video driver — that disables 3D support, including CUDA.
The workaround I found was to use UltraVNC — a free remote-access solution. It’s slower than Remote Desktop, but doesn’t interfere with the native video drivers (and running three video cards with one monitor is experimental enough, without Windows periodically pulling the drivers out from underneath everything.)