I was able to play Megarace 1 withe 360 controller. Navigating the menu is the only problem I had, but during the races, just use the left stick to drive and steer and A to shoot.

Megarace 2 is a bigger problem though. I can't get the right calibration so I can't really control the car during the races. So if anybody can help with that, much appreciated.

In retrospect, I realized something. With Megarace 1, I had already had the controller connected and just started playing with the controller right away; I didn't tinker with the options. In Megarace 2 though, I mess with the option and didn't try playing with the controller right away. Maybe that was the problem? I haven't checked yet because I've uninstalled the game as I'm playing another game right now.