The .45 is too much for the hull, and the VX-M is really pricey for someone starting out. Consider starting with this one (you'll also need a tuned pipe):
http://www2.towerhobbies.com/cgi-bin...?&I=LXALL8&P=7
and learn to tune the hull and engine to get the most out of both of them. This engine will allow you to run in B mono, if you're planning to race, and will be a good match size-wise, with your hull. A .32 would be ok for fun running, but if you compare the numbers, the .32s don't really have any power advantage over the better .21s.