http://wetab.mobi/en/

It's a German touch tablet, based on the EXoPC. It has 1.66 MhZ Intel Atom processor (same as in some netbooks), an 11.6" widescreen format touchscreen, multi touch, has 2 USB ports, SD card slot, 1GB RAM, 16 or 32 GB SSD storage. WiFi or 3G and GPS.
It comes preloaded with the WeTab OS. The WeTab OS is fun to mess around with, but ultimately it's no good as a productivity tool, especially for music. Luckily it can be dual-booted or replaced with anything. I have tried various versions of Linux, a few "specialist" touch screen operating systems, and Windows 7.
Windows 7 means I can plug in my sound card and midi keyboard (I use an X Station keyboard/sound card combo), and have a very mobile, but fully capable, mobile music setup. I have started using it with a band, using Chainer and a few VSTi's for live playing. It's quite underpowered compared to a desktop, but Reaper runs on it just fine. I haven't tried Ableton Live yet. So far I haev used it with 1GB, but it can be upgraded to 2GB which costs 25 euros. If so inclined, larger SSD can be added (although it's a bit expensive at the moment).
WeTabs can be had for around 220-250 euros for the 16GB WiFi only version, 50 euros more for the 32GB Wifi/3G/GPS version. This is a relative bargain when compared to similar devices. Check German (.de domain) shopping sites. The prices fluctuate quite radically, as the price dropped recently from something like 429 / 549 euros.
I believe I might be one of the first to try this setup for live music, but i'd be really interested to hear if anyone else has tried it.
And by the way, contrary to what I had been led to believe, touchscreen implementation on Windows 7 is very well designed. This was a nice surprise for me.