This is a Worm affecting Windows XP and Windows Server 2000/2003. The worm spreads by using an exploit in the Microsoft RPC. You should make sure all of your windows updates have been installed to help avoid worms such as this.
The W32.Wecorl worm will copy itself to a .dat file and will also create several registry entries. Once a computer is infected, the worm will attempt to download files from various remote sites. These files will be saved to a temp folder. The worm also attempts to infect other computers on the network.
To avoid worms such as this, keep Windows automatic updates turned on and run a regular scan of your PC.
