I have an Asus EP121, and I *love* it. It's one of the ones that uses wacom components/drivers.. so the responsiveness and pressure sensitivity is really great. I'm really, really surprised I don't hear more about them... but I guess it's a niche machine.
I got mine factory refurbished from the Asus e-store pretty cheap (comparatively). If you search youtube for it there are some great videos from artists comparing it to a Wacom Cintiq--favorably! They're what convinced me to go for it.
Here's a picture I took while working in Photoshop on mine... [link]
dont forget about the motion computing le 1600 and 1700 tablet pcs............they are awesome for drawing i got one a few months back and im like wow very very responsive and no lag unles you use photoshop to draw (or use a thousand layers) but its good i use sketchbook and sai. Also its the cheapest on the market i got my for $75 used just for a small crack on the screen and the go from there to $185. i think the most expensive is like $400 new but why buy new ones when the used ones are very decent. plus its an excellent alternative to the wacom cintiq 12x because its a 12 inch screen as well almost $800 cheaper
Also let m say that even though i named those tablet pcs if you got the buck i want you to not just buy any penabled tablet, because not all are designed for artists......the ones named here are very common names that i came across earlier this year when i was looking for one so these are good. but i thought before i did my research that any tablet would do and got an asus transformer and some kind of acer tablet and both werent half as responsive as a bamboo tablet (dont worry i took em back but was still pissed when i got home) And asking some employees if it is wacom drivers in them and they more than likely never heard of them. Personally i forgot to mention if you are still looking is the samsung galaxynote 10.1 (with the s pen dont forget to ask that there are different models and the one without it you cant draw on the screen). I bought that back in september and omg the most wonderful thing in the world like wow it is pricy being around $400. but it worth it and it has wacom drivers in it too. Sketchbook works like a dream. Just go on youtube and look up drawing on samsung galaxynote 10.1. I personally dont like the Mac OS and prefer the Android OS so just an alternative if you want a newer tablet. I dont mean to talk too much but i just remember searching forever for the right and cheap tablet to draw on and i went through too many wrong ones and wrong information before i got what i have now.....
im not really getting your question but let me see if i can try..... since the tablet pc that i named have wacom drivers in them it works pretty well for any OS (operating system such as windows 97, 7,8, or MAC).but dont worry about that in fact you dont have to install them they are preprogrammed within the tablet pc. the older tablet pc that i just named comes with the OS of windows vista but its not much different to that and windows 7. Dont get me wrong if you want a new OS you can always go out and buy it just like any other computer but why spend the money.
So point is the only tablet you need to install drivers on any computer in order for them to work are the graphics tablets not the tablet pcs i named. Which those are like the bamboo and intuos models. But even for those they design the driver download to work on numerous operating systems at the same time Look here on the wacom site and you can type the model and make of the tablet if that is what you are going for >[link] HOPE I HELPED LET ME KNOW IF YA GOT ANYMORE QUESTIONS
If you want a proper "classical" Tablet with keyboard, take a look at the Lenovo ThinkPad X61t or X200t. If you need more performance, look out for a used X201t, though they can still be a bit expensive, at least for my taste.
Wait for the 32-bit and 64-bit Windows 8 market to expand more. Personally I'm planning to replace the laptop I currently have for my university studies with an ASUS VivoTab or Transformer Book and use it as a sketchbook as well as a student notepad.
There are plenty options for you. Any pen-abled tablet pc can serve your need. It should be better if you are more specific about your requirements.
For leisure sketch, I recommend Atom-powered slates such as HP Slate, Fujitsu Q550 or the current Samsung ativ 500t for their long-lasting battery life, light weight, silence and accessibility to x86 applications. Alternatively, you might want to look at the pen-abled Android tabs, namely Galaxy Note, Thinkpad Tablet and HTC Flyer.