What about the HP Slate 500, with a leather case that doubles as BT keyboard?

Its actually the best possible (x86) tablet you can buy with only 1 major flaw= 2-cell battery.
If they had included a 4-cell battery, enough ram, and a speedy SSD... then it would be quite responsive (especially with Ubuntu Netbook Remix). The interface problem is software only and can be solved with a KDE overhaul if you're willing to get your hands mildly dirty.