Problem with Insurgency Maps in Gmod

Hi there!
Call me stupid but i have no idea how to install Insurgency maps correctly.
Is it possible to play on them with the latest Gmod?
Everytime it gives me a CTD with the error message
“failed to lock VERTEX buffer in CMeshDX8::LockVertexBuffer” Any solutions?

I know here are a few guys around who are actually able to play on them.

specs :
Vista 32 bit
AMDx2 4600+
2gb ram
8800GTX 768mb