The normal Millenium G400 is available in 16MB and 32MB versions with a 300MHz RAMDAC. Matrox doesn't disclose core and memory speeds, but general online consensus has the normal G400 clocking in at 125MHz for the core and 166MHz for the memory.
You can find OEM versions of the G400 with and without DualHead (dual monitor output), but we highly recommend getting the DualHead version, because the dual monitor output feature really makes this card. Right now you can find online vendors selling the single head 16MB version for only around $100 and $150 for the 32MB version, but you might be better off with a TNT2 if you don't want DualHead. Then again, the new TurboGL driver does improve the G400's performance up to TNT2 and V3 levels in games based on the Quake II, Quake III, and Unreal engines.
Millenium G400 Max
The Millenium G400 Max is available with 32MB of SGRAM and a 360MHz RAMDAC. Online consensus has the Max weighing in with a 166MHz core, and a 200MHz memory clock. The Voodoo 3 3000 has a 350MHz RAMDAC and a 166/166 core/memory clock. The standard TNTU has a 150/183 core/memory clock and a 300MHz RAMDAC.
Matrox has always been known for having the best image quality and that hasn't changed with the G400, but OpenGL driver problems have nagged users ever since the G200. The new TurboGL driver is just the first step towards the full OpenGL ICD. Matrox has a team working on the full ICD while another team is doing the TurboGL mini ICD. Eventually the mini ICD will merge into the full ICD.
The Marvel G400-TV is the new kid on the block. Following in the footsteps of the Marvel G200, Matrox's Marvel G400-TV is the all-in-one video card for the home user with an interest in capturing and editing video. In addition to a TV tuner, the Marvel G400-TV offers hardware MJPEG video capture and editing.
The Marvel G400-TV is powered with a normal G400 chip and comes with 16MB of SGRAM. Matrox doesn't plan to release a 32MB or a Max version. This is understandable because the Marvel G400-TV is more of a mainstream product. Sure, plenty of gamers would be interested in the marvel, but there's a larger mainstream market out there that wants video capture/editing and could care less about gaming performance.