Hello!
I created a test page and the ComboBox looks very strange and big on my side.
Here is a screenshot of your sample page when it is using Web20 skin: http://picasaweb.google.com/botondlong/TelerikSkinWeb20#5384996291258328274
I haven't done anything special: I have a masterpage with the RadScriptManager, and I have a RadComboBox, Skin set to Web20.
With further investigation I found that RadDatePicker is behaving the same: a big input box and the calendar itself is also bigger and looks quite ugly.
I checked, there is nothing related in my css or skin file. Where can be the problem?
Btw, I'm using RadControls for ASPNET AJAX Q1 2009.
Thanks
Botond