Moved to the lounge as this isn't Android specific
I am guessing the tablet you saw was this one http://www.amazon.com/ASUS-Slate-EP121-1A011M-12-1-Inch-Tablet/dp/B004HKIIF8
, it seems to me you would get a better deal with a laptop. I am not sure what you will be using the device for specifically but other than that tablet being cool for being a tablet you can get better specs for less if you go laptop.
I don't think you will be able to get a dual boot window/android you may be able to get a windows/linux on the tablet but I wouldn't expect it to be easy.