Filtering Category Results

Hi, im using a category template to display a list of post for a chosen category, which is all fine,

What Id like to do is then filter that list either of 2 taxonomies i’ve set up,

Device – which would be a drop down of device types

and charge – which would be radio button toggle of “Free or “paid for”

Something like
http://appworld.blackberry.com/webstore/product/1/?region=74&lang=en

Many Thanks in advaNCE