Take a look at this:
Segosa's reply to Idea for Patchou msg3
Please note, patching/altering MSN Messenger is against the Terms of Use you agreeded to when installing MSN Messenger. I am, by no means, responsible if Microsoft comes after you for altering their product, nor am I responsible for any side effects suffered to you are your computer direct or indirectly.
Proceed at own risk!
Resource Hacker
Close MSN Messenger before doing this
--> Open C:\Program Files\MSN Messenger\msglang.dll (or wherever you installed it to.)
--> String Table
--> 45
--> 1033
--> Remove 708 and 709 hit compile script and save.
When doing this MSN Messenger will not prompt you to close the windows it does it for you.