If you want to add additional space to record programs onto, then yes, you can. Simply purchase a PVR Extender at one of the Rogers Plus locations. They come in two capacities at the moment, 500Gb and 1Tb. This will give you roughly 4x-8x the current recording space you have. Simply plug it into the back of the box and into a power outlet and the PVR and the drive do the rest of the work. Be aware, however, that the recordings are encoded to the specific serial number of your PVR and cannot be read by another PVR or a computer.
If you want to view the PVR recordings in another room, this is not something that Rogers provides at this time.
I'm not sure on the prices rogers charges for an extender but you can also just buy a hard drive and an external enclosure that has an e-sata connector. Then you just plug it in the same as the rogers one and it formats and is ready to go after a reboot of the pvr. (Reboot being a full power off/on)
You can purchase a Western Digital PVR extender at Best Buy. It has 1TB in recording space and is about $60 cheaper that the 500 GB box sold by Rogers. It uses the eSata connection on the back of the PVR.