The problem is that CM has a problem with the DX 10 calls involving nVidia cards. In Windows XP it runs fine, because DX 9 is in use. Keep in mind that CM actually uses something like DX 5, but is compatible up to DX 9 with nVidia.
So, with Vista, your video card is using DX 10 calls, which are broken with respect to CM. So, your best bet is to use an ATI card. I am running Vista 64 with an ATI 4800 and it works great other than having to get the bmp fix for the text problem. At least you have fog too this way. I have been an nVidia guy for years, but, if CM is important to you, you don't have a lot of choices.