Game Development Environment?...

I’m starting do game and Silverlight development and need to now how much RAM needed for the Host and to allocated for the GUEST?

The software I will be using to create my games are Softimage ModTool XSI 7.5, Gargage Games Torque X 3D & 2D and Torque 3D, MS Expression. Running Windows Vista Ultimate SP2.

Right now my Host RAM is 8GB (7.5 for use) and allocated 4GB (3.5 for use) for the guest.

Any recommendation?