I bought a N800 and two 8GB SDHC cards and an iGo Bluetooth keyboard for a total of less than $310.

The touch is a nice MP3 and video player, but unless you hack it to add other applications you're limited to what it can do.

The N800 on the other hand needs a little more work to get working how you like it, but the browser (after adding Adblock Plus) and a couple of other tweeks works very well. There are other applications such as Maemo Mapper which you would have had to pay $$$ on the Windows Mobile platform. The eBook reader (FBReader) is also excellent if you have compatible (DRM free) files. MP3 and video playback aren't quite as smooth as the iPod, but with Canola2 things may get pretty close fairly soon.

There is currently no PIM applications to match the PocketPC apps like PocketInformant, but there are enough to keep you going. There are spreadsheets and note apps to meet your requirements.

Hope this helps.