I posted a similar type question on another forum and the advice (from a personal trainer, who has done CD before) was not to do too much cardio (moderate only), whereas resistance training was okay.
Her view was that cardio exercise should only be done if on the 1000 plan or higher.
I'd say, if you really want to do a bit of exercise - listen to your own body (so if you feel lightheaded or unwell - then stop) and more importantly if you find it stalls you, then leave it alone until your closer to goal or on the higher plans heading into maintenance.