Spokewench is right - most of us race through the season, and THEN transition to 'cross racing. I start my race season now, and race on the road and MTB through August. Then it's time for 'cross.

And LOTS of interval training is what you will need. Riding your MTB is also good advice - as SK said, if you have the fitness, but lack the technical skills, you won't get far in a race.

FWIW - I don't run. Ever. I only run in a race, and since it is short, and my fitness is good, I don't find this to be a hindrance.

SheFly