Someone asked about tablet PCs for art yesterday and I tried to write a decent answer. With the surfeit of net slates, iPads and the like coming down the pipe, it's easy to forget that the tablet PC, Bill Gates' baby, still exists. These aren't mainstream items and there is next to nothing out there written about using them for art. Which is daft, because many models use the same Wacom technology as an Intuos or Cintiq tablet.
Because they're mostly used in business contexts and are purchased in bulk by organisations, they tend to filter back onto eBay after a couple of years and you can often find the most popular models in some number. So long as it's not a beater or ancient, put in some more RAM, a new hard drive, maybe get a nice Photodon screen protector and you will have a wholly serviceable computer for drawing and making comics on.
You need to make sure you get a model with an active, not a passive digitiser (passive digitisers just respond to physical pressure, ie your elbow, a stick etc) here's a master list of all the models that are decent for doing art on. Most tablet PCs have 12.1 or 12" screens and while there are still some models floating around with SXGA+ (1440 x 1050) screens, don't buy one if you value a. your eyes and b. the time you will spend fruitlessly recalibrating the screen to try and hit your mark. I never could. To get pressure sensitivity in Photoshop, you need a Wacom Digitiser (not N-Trig, which a few models employed).
SUGGESTED MACHINES BY PRICE!
I AM POOR (Most of these won't run Windows 7 satisfactorily due to missing drivers for video cards etc):
Toshiba Portege M200
Hundreds of these out there. They all look a bit worn out. Nice to draw on. Horrible screen viewing angles. Hi-res screen might hurt your eyes.
Lenovo X60t (make sure it's a "T", the standard X60 was a regular laptop)
Tremendously robust glass screen and IBM build quality. Screen bezel a bit annoying.
Fujitsu ST5022, ST5032
Crappy specs, annoying PATA (hard to replace now) hard drives, really really nice to draw on. A compromise candidate for £200. Abundant.
I HAVE A FEW HUNDRED POUNDS TO SPEND
Toshiba Portege M400
Good all round drawing feel and nice screens, esp. in the 4220. All the Fujitsus come with two button pens (many tablet PCs just have one button pens that feel like they are made out of a drinking straw). Again, nice to draw on.
A revision of the X60 above
As above but SATA hard drives, maybe a Core Duo processor, you can put Win 7 on it
I AM RICH
Fujitsu T5010/T900 (core i version of T5010)
This is the only 13.3 inch widescreen tablet left, I think. It's heavier to lug around but the extra screen real estate is very nice.
12 inch widescreen (like a Cintiq 12WX screen)
Widescreen HP business machines with good build quality
There are newer models from the main manufacturers that I have not had a chance to have a go on. Of course manufacturers should feel free to send me complimentary devices.
MACHINES TO AVOID ON ACCOUNT OF "ISSUES"
Toshiba Tecra M4
Video card burns out eventually, hinge is fragile.
Toshiba Tecra M7
Oversensitive pen feel problematic in some applications (Manga Studio particularly), a lovely computer but this was a flaw I couldn't get past. In Photoshop it seemed fine though and I managed to make about 40 comics on mine while on the road - it took a bit of tweaking. The 14" screen was mega though.
Great to draw on, big screen, but there was a recall of many of these because the cursor would stick in the corner of the screen.
Axiotron Modbook (kind of a cannibalised MacBook slate)
Text input via pen on a slate is important and it's excellent under Vista and Win7. The Modbook's text entry is not great. Not great at all.
I would advise that you avoid machines with pen and touch or "multitouch" options. If you want to touch something, TOUCH SOMETHING ELSE. The Wacom enhanced drivers barely work on most tablet PCs, the dual touch drivers are prone to explode. These aren't mass market consumer machines and issues in this area, when addressed, have seldom been addressed well. Hopefully my list will help.
Every make of tablet PC I've used has had a slightly different feel to draw on. The Fujitsus are closest to the Cintiq but a combination of anti-glare screen coatings etc fogs the water even there. I've no idea about Motion Computing's slate offerings but they are supposedly very well made. I've never seen an "Electrovaya Scribbler" or an "Armor X1" so who knows.
When you buy a tablet PC, buy it as a drawing machine, not a laptop. This part of the market never really took off and the best machines are not always the newest. There are crazy people out there still using HP TC1100s from 2002 because they love the form factor so much, and it was never replaced. They are completely insane but I hope it illustrates my point.
I hope this helps a few people! If I've raised any questions, stick 'em in the comments.