With the recent release of the Xbox 360 Wireless Speed Wheel at an entirely reasonable AU$59.95, this seems like a golden ticket.
Overall, I find the bog-standard Xbox 360 controller to be fine for enjoying a game now and then, but something a little more immersive would be great. I put myself into the 'loves a good racing game, not hardcore about it' category. Just be prepared to put up with one deeply annoying exclusion.
Do you like racing games? But not quite so much you'd buy a serious racing wheel system? The Xbox Wireless Speed Wheel might be exactly what you're looking for.