Ok, you may have been through this before and Im sorry, but with the new new machine...
What are its hardware specs? (cpu, ram, video)
Have you installed the latest directx9c? (Nov 2008 I think)
Have you run the DXdiag utility hidden in directX? Did all video tests pass?

Also, you installed a new windows. What version, XP or vista? Any service packs?

You also loaded all drivers etc, so what other software have you loaded?
(Microsoft Office, etc) Try to list everything in case something is interfering.