Windows XP users can download the new version of Windows Messenger a few days early this week; Microsoft has quietly launched the new product, which features .NET Alerts compatibility and other new features. Windows Messenger 4.5, which is now available for XP users only, provides text, audio, and voice-chatting capabilities. (Windows 2000, Windows NT, Windows Me, and Windows 98 users can also download a similar update to MSN Messenger now.)

For XP users, however, the new release includes some features that MSN Messenger users are already enjoying, such as .NET Alerts and integration with other features such as stock quotes through a tab-based interface. But Windows Messenger 4.5 adds several unique features, including the ability to organize contacts with built-in, customizable groups and make PC-to-phone calls (this feature will be available October 25).

XP users can download Windows Messenger 4.5 now from the Microsoft Web site.