NeoWin are reporting that English/U.S version of MSN Messenger 4.5 has officially been launched for Windows 95/98/ME/NT/2000. The XP version will not be available till Thursday although NeoWin have been able to install this on XP and its working fine (with enabled alerts).

Update the XP version of Messenger 4.5 Final is available. So hit the Read More button for your download: Apparent changes:

Sidebar is on by default with all new messages.
Resizing of Message window is limited.
.NET Alerts functioning

Download: MSN Messenger 4.5 v4.5.0120 US/EN Version

Download: MSN Messenger 4.5 German Release

Download: MSN Messenger 4.5 French Release

Download: MSN Messenger 4.5 Italian Release

This version of Windows Messenger can only be installed on the Windows XP operating system.

Download: XP MSN Messenger 4.5 v4.5.0120 English Version

Download: XP MSN Messenger 4.5 German Release