winter training in Denver area?

I grew up in Denver but have spent my entire triathlon life in Houston.  I've got the opportunity to transfer back to Denver for work, which if I'm offered I will take, but I've signed up for a few Houston races where I'm really nervous about training for in Denver.  I won the lottery for the Houston Marathon (my first marathon, Jan 30), and I registered for the inaugural Ironman Texas (May 21).

I'm not very excited about training for either of these by myself, especially the marathon.  Most of the running/cycling groups websites in the Denver area seem to only go through October.  Are there running/cycling clubs that are active through the winter, or will I be doing my 20 mile runs by myself in December?  I will likely be moving to south Englewood, Highlands Ranch, Centennial, or Littleton.  Don't mind driving some, but would prefer to stay south of Denver.

Then of course there's getting used to the cold, running at elevation, having to do actual hils, buying cold-weather gear, not being acclimated for IMTX heat in May.  But I figure I'll worry about those details when the time comes.  Right now I'm stoked about being able to move back home AND have a job already in place.