I think you already answered your own question.
If touch/tablet functionality is the deciding factor for you I'd go spend some time with a few tablets and then mull it over.
I've used tablets before and was fairly satisfied with more recent models, but I don't find it to be a killer application. You may have different thoughts.
Netbooks -> Mini 9 - 2gb Gskill low latency - Ubuntu 8.04
Asus Eee 701 4g - 1gb - Ubuntu 8.04.1
Desktops -> Phenom Quad @ 2.8 - 16gb - 4x Raptor X in RAID 0 - 2x 4870X2
Brisbane 1.9 @ 2.7 - 4gb - 80gb
Many others, all Linux.