I saw that AR9 under Linux offers tabbing (opening several files under the same window with each having a tab of its own).
Does such an option exist for the Windows version?
(I'm using WinXP with AR 9.2.0)
I don't think this option is available in the Windows version. As I mentioned in my comment I have version 9.2.0 installed and can't find any options or preferences for opening in tabs rather than new windows.
I don't know about Acrobat Reader, but Foxit Reader is a freeware pdf viewer that opens multiple pdf in tabs. It seems a bit quicker to open documents than AR as well.
I know it's not a solution to the AR problem, but it is an alternative option...