Oh Tom, just install ICQ.
I have it and use it only to sending big files, cause it is more stable to sending big files and plus it has reasume thing.
So no big deal if your comp die in the end of sending 20 MB video.
Tom once my ISP blocked my MSN and I just changed the port by clicking the Tools Menu on the MSN Messenger, click on Options, choose the Connection tab .... IMPORTANT: Copy all the current settings first before altering anything for easy roll back
Then click on I use a proxy server (Depends on how thw settings are - Choose SOCKS Version 5 and set a high number port eg 3190 or something then give it a try.
Your firewall might raise all sorts of alarms at this point. And again this port might be closed at your ISP