I have installed 2.64 on a Win 2008 64 bit server with nVidia GTX 570, and it runs smooth as silk.
However, If I start Blender on the console, ie. keyboard attached to the server, I get GPU.
If I start Blender by placing it in the Startup group, I do not get GPU.
Or if I start Blender while in Remote Desktop connection to the server, I do not get GPU.
So, for now, I have left Blender running with the startup cube and cut the remote desktop session, but if the server boots, I must go to the console (a trip to the University) and start Blender.
I am wondering if there is a command line startup switch that would force Blender to use the nVidia (which is lightning fast by the way, the clay render of this mail took like 30 seconds and not the 18 minutes on my laptop)?
There's a workaround - use Splashtop Remote Desktop. Free for personal use, it also allows you to access the NVIDIA Control Panel.