Making old games run well can be hard sometimes, here's some things you can try for this game:

• Running it in Windows XP
• If the game is not working well with the main exe "Mechanix.exe", try the second exe "MechanixSW.exe"
• If neither of the exe's are working perfectly, try adding some compatibility settings on the exe's

Personally I've made mine run perfectly just by using VirtualBox with Windows XP sp2. It was not necessary for me but you can also install Virtual box's Guest Additions Direct 3D support (to install it you'll need to be in Safe Mode, press F7 or F8 while booting). Increasing available Video Memory in the VirtualMachine settings might help too.