I’d wait a few months for Windows8 - Both Samsung and Asus are prepping upgraded versions of their slates to suit Win8 requirements.
I like the bigger screen of the Asus but battery life and a questionable GPU have held us back from buying a few. The Samsung seems better-put-together but is smaller (if we’re gonna sketch on it, bigger really IS better…).
I just saw the Windows Surface slates…interesting. http://www.microsoft.com/surface/en/us/default.aspx I like the integrated cover/keyboard and the i5 non-arm version supposedly will have a stylus.