So far, there haven't been any reported widespread issues with any of the OFFICIAL updates through WU. Be sure to keep checking the list in the link above as new updates roll out.
wu well i installed the malicious software tool and all the updates and have had no trouble,have modded bios, dell slic and key.
Rumor is that malicious software tool is designed to only track down worm based virii and other things that clog up corporate machines, not used for attacking pirated software.