Hi Diver,
I am sorry to inform that you will not be able to use Windows Messenger in Windows 7. Windows 7 does not support the lower version of Windows Messenger. You will have to install the latest version of Windows live messenger to work with Windows 7.
You may access the link below and download the latest version of Windows Live Messenger and install it.
http://download.live.com/?sku=messenger
Hope this helps.
Thanks and Regards,
Srinivas RMicrosoft Support.
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