I've tried doing the heavy weights first and then cardio after (read on here to do weights then cardio) but I had DOMS like you would not believe!!! I couldn't go back to the gym for 3 days. When I did go back, tho, I did cardio first then weights and only had very mild DOMS, and back to gym for cardio-only the very next morning. I would strongly recommend doing some warm up cardio, then weights, and maybe cooldown cardio after that??

Just my opinion, of course!

Nicole