You ever wondered that Messenger uses Windows Aero frames since the 14.0.5027.908 beta in September? You want the original Messenger frame back, but you don’t want to disable Aero completely in Windows?
The solution is: Use the Messenger Aero Switcher. In order to use it, you should be on Windows Vista with enabled Aero, and you should have the latest Windows Live Messenger 2009 RC (14.0.8050.1202) installed.
Free download: Messenger Aero Switcher for Windows Live Messenger 2009 RC 14.0.8050.1202 (165 kB)
Please report any problems or unexpected behavior you might notice.