My Dish 501 PVR uses a RF remote, but also responds to commands from an IR remote for a Dish 301 receiver. Can anyone tell me if the PVR functions (play,rec,skip,etc,etc.)respond to IR rather than RF? IE: is there a remote on the market that can be programmed to do the Dish 501 PVR functions? I am assuming most all programmable remotes use IR only and cannot be programmed to learn RF. Am I correct?
Thanks!!

All of the functions on the remote including PVR are sent by the remote, and received by the receiver in both RF and IR. You can use any remote capable of importing the associated commands, or learning the to send IR commands to the 501.

Yep, I just bought a Pronto TSU-2000 and it accepted all of the IR codes without a problem (I also have the PVR 501). You can also find some pretty cool files that allow you to "surf" to channels based on clicking on a station logo icon (you program the remote to do the keypad buttons for you). So when you click on the Sci-Fi channel logo, for example, the remote sends channel 122 to the PVR.