For PVR you could also look at
This from Futureshop, but it is 3/4 the cost of the AIW your looking at. And NCIX has
This, but their site is damn slow tonight. Same card that Traire linked to (ATI hardware mpeg2 encoding) just different reseller. Note these do not work with ATI Multimedia Center that the AIW uses, but do work with bundled software and other 3rd party PVR software better than the AIW.
Another option, depending on what you use the second monitor for, is a PCI video card like an original radeon, which you should be able to get for next to nothing., with the AIW. There may be limits on if you can only extend your desktop to the second, I can't recall. I do know you can't put the TV on the second this way, or I couldn't (or games). May have been a directx thing though. Works ok for browsing, docs, music, etc... I'd borrow an old pci card first and try it though but find one that is at least a Radeon or above.