I've never found VNC or Remote Desktop to be too slow on all of my machines. (Though the N900 does sometime take a bit longer than desired to get updates from the screen. Over my house WiFi it works fine, over my university network [wifi from N900, ethernet from laptop], gets a bit less usable, but not badly enough to make it unusable.)

But BlueMaemo is probably a better solution if you're doing it from bluetooth range.