Msn Messenger Download Mac Os X

I have only just started using mac, my desktop computer is a windows pc and I use msn video conferencing to talk to all my rels back in UK.
I am having real trouble dowloading a version of msn messenger for mac that will work. I can type talk but when we try to have a video conversation it says that I am not using the latest version of msn messenger.
(phoned msn to ask what the latest version of msn messenger for mac was and she said she could not tell me!!!!!!!..weirdo)
any ideas? tx