Cool, if you check my blog, that is exactly what I do, and have been told to do by my trainer as well.
I do my specific muscle group weight workout for a given day, then I follow all of that with my 45 minutes of cardio.
I do that Mondays, wednesdays, and fridays, and on the off days, I just do the cardio.
At the end of Jan. 06, I'll be at my optimum/goal weight, and it is then that I'll be starting my toning/higher-strength phase.
Good luck!
Israel "Izzy" Long
Motion and Title Design for Broadcast-Film-DS
izzylong.com