I think your goals also factor in greatly. If building muscle is your goal, lifting weights and then getting out and getting in proper nutrition is vital, ASAP. If fat loss is your goal, I think a 20 minute run after lifting is fine. I've been doing that for over 2 months and haven't lost a shred of muscle, while losing quite a bit of fat. Either way, I agree with goergen that if you have solid lifting routines, with or without cardio, you will see results...