W32/Checkout!12942F6 is a worm that spreads via MSN Messenger. When installed, it sends one or more of the below messages to contact list recipients and send a malicious zip file named myalbum2007.zip (~52 KB).

This worm attempts to detect the infected system's language settings and send instant messages with the corresponding language, and zip attachment.

More information can be found at this McAfee page.