Don't know if you are still looking for some game dev pc specs but here is what I've found in terms of what would be needed to run the two programs together.
This information came from Microsofts own website:
To run XNA Framework games on Windows, you will need a graphics card that supports Shader Model 1.1 or greater and DirectX 9.0c. We recommend that you use a graphics card that supports Shader Model 2.0 because some samples and starter kits may require it.
Here is microsoft's
website for more specific details.
This information came from Garage Games website:
1.0 GHz processor
512 MB RAM
Windows XP Service Pack 2
Visual C# Express 2005
Video card supporing DirectX 9.0c and Shader Model 1.4
2.0 GHz processor
1 GB RAM
nVidia or ATI accelerated 3D video card
XNA Creator's Club membership is required to run your Torque X games on an Xbox 360.