I really need something relatively low impact as my knees can't take much these days. I have very little time to devote to exercise so I think a cardio/toning program will work well for me now. Any recs? I have dumbbells and I'd love something that incorporats weights if possible. Thanks!

The Biggest loser has alternating cardio and weight sections at 2 levels and I think was about 20-30mins long.

Jari Love DVDs are weights but she does high reps so it's cardio like too (some more then others) hers are longer though 45-60mins most of them.