If you want a tablet, take a look at the $350
Nokia 770 or it's soon-to-be-released
successor. Outstanding for web, email, rss, audio and video, PIM apps too - pretty much have all the functionality of most laptops, and also work great with Bluetooth keyboards.
Check out
Canola which is a new media front end for the 770 - it should be released in a few hours (launch date is 29 November - the developers didn't specify a time!) and will of course be totally free! :)