Andre de Costa points out MSN Messenger 7.5 is available for download here:
"The MSN Messenger team have just released version 7.5 of the client to the masses.

Among the new features are Dymanic Backgrounds and Voice Clips. Dynamic Backgrounds fill your MSN Messenger conversations and subtly animate during the conversation. Voice Clips allow you to send short audio clips (15 secs max) to your friends on MSN Messenger."