At first blush, I would have guessed that the Quadro would be the better card. However, after looking at the specs, it's pretty clear that unless you are looking at using an application that's likely to fill the 64mb texture buffer, you will be better off with the 400MX. If you are just looking at MAME, either will work (as Savannah already said). If you are looking for other stuff too (especially more demanding/modern stuff), you'd be better suited to invest in a cheap modern mobo with onboard graphics. Even a modern onboard video solution will outperform either of these cards by FAR.