We have deployed three of the Ipad solutions so far with much success.
Yes, its remote desktop to a virtual machine. This insures that the information never leaves the BOH and PCI compliance is retained on the BOH machines as the CC data is never transmitted over the air. I'm running the VM in a VMware cluster (overkill) but you can definitely run this on Virtual PC (FREE) and VirtualBox (Also Free). I did have to buy the WS licenses as it is another workstation talking to the database.
I recommend jailbreaking the Ipad if you're going to do this. At least in my case, the first time I deployed it, the servers were using the ipad for other things. Jailbreaking gives you the ability to run an app called Incarer and lock down all the other Ipad features (IE:Safari, Itunes, Appstore).
As far as printing goes, we have a couple ip based printers from Micros. I'm working on the mag reader option now. Currently, CC payments are done at another terminal unless the server keys it in (Rarely).
The reason we went with the Ipad was the low cost and reduced complexity (and the occasional awe). We have two MC55s ($3K each) and they are not easy to work with. I'm trying to get the mag reader to work and its temperamental at best. If anyone out there knows anything about the these handhelds and the mag reader, please PM me or chime in.