The terms are pretty clear - if you got your receiver after they changed to the 2 year commitment for advanced receivers (HD, HD-DVR, SD-DVR) you'll pay a $300 early termination fee if you cancel within a month. After that, the fee drops by $12.50 a month (or figure $12.50 x months remaining under contract). In lieu of the fee, you may return the equipment that is under contract - and you are free & clear. If your equipment is under the old 12 month commitment, it's the same deal, but the fee starts at $150.
FWIW, the return of equipment normally doesn't make sense except perhaps with an SD-DVR. Make sure you check the ebay market before deciding which route to take.