It's possible that it's a DirectX problem. The TNT2 is a DX7 or DX8 card, and there might have been some lingering compatibility problems with DX and Win2000 that weren't cleared up until DX9, however...Unless you want to upgrade your video card sometime soon, I recommend that you leave your DX8 in place for now. You can always upgrade later, but once you install DX9 it is *very, very* hard to revert to DX8.
Instead, I suggest that you first look at your video drivers. nVidia keeps updating their drivers to enhance the performance of all their cards, but their focus is always on their newer ones. This means that sometimes older cards or older configurations lose compatibility or performance.
Have you updated your video drivers since you installed it? Go to your Device Manager screen (Control Panel -> System -> Device Manager), click on Display Adaptors -> nVidia TNT2, and choose Properties. Choose the Driver tab and click on the Driver File Details button. What number is given for the File Version?
When you do manage to get MM9 working, I suggest you insatll both the official 1.2 patch and TELP's 1.3a patch. These will prevent many of the bugs that gave the game such a bad reputation. Go to TELP's main page at telp.org/mm9 and click on Patches. Both patches are available from there.
