Hi I signed up for this forum just to answer yoru question as I thought it was interesting that the moderator didnt know what wextract was.
Wextract Cleanup0 is valid and legal software included or sold to help clean up temporary or cab files created by the installer software for a wide variety of software.
Wextract is a Microsoft file depending on what version of windows you have Im guessing xp its probably in the system or system32 folder cant remember which. In win 2000 its in a dllcache folder.
It basic puropse is to clean up cab files. You know the great WIndows updates. They leave things behind sometimes and wextracts job is to clean them up.
Hope that helps.
so to answer your question NO Wextract is not some virus or trojan thing left over. Its a Windows Microsoft file and you should allow Search and Destroy or adaware to allow it to change the registry because its doing its job of clean up