Hardware Required for Internet Connection?

I have confirmed with a DTV rep a few weeks ago that my DVR has the capability of internet connections (I have the model prior to the current HD-DVR model).  Specifically, I want OnDemand and PC access.

However, I've not found the same Cisco hardware that is advertised at DTV's site in any local store.  All I can find is USB adapters to allow access to my home wifi network.

Amazon does offer the same hardware, but my question is...is that my only option (for wifi)?  I cannot seem to find a definitive answer on this.

Can I buy a USB adapter at Best Buy and hook up my DVR to my network?  I'm trying to do this as low cost as possible.

Thanks.