For artists serious about having a powerful, portable tablet, I stumbled across this: http://www.scribblertabletpc.com/model/SC4100.aspx
It might seem pricey, but this thing packs a wallop.
This thing packs all the features of a decent laptop into a slate formfactor.
- Dual digitizer (pressure-sensitive WACOM or touch - that is, a true WACOM device)
- Up to 4GB RAM
- 60 to 160GB SATA internal hard drive
- 2x USB ports
- PCMCIA card slot
- Wireless G and Bluetooth
- built-in webcam
- Windows 7 Home Premium
You'll be able to run all your high-end graphics software (ArtRage, Photoshop, Illustrator, Painter, the full version of Sketchbook Pro, what-have-you), color-calibrate your screen, go mobile with a PCMCIA cell modem, etc. USB ports for external storage and alternate control (keyboards, etc.).
This is not an e-reader, mobile app platform, or mobile web browser - this is the full meal deal. My laptop budget for this year may just have to get extended.