What is it?
Windows Update Automatic Client - wuauclt.exe
What does it do?
wuauclt.exe - This is used by the automatic update tool in Windows ME to check the Windows Update site every so often to see if any updates need to be installed.
The original wuauclt.exe from Microsoft gets placed in the Located at C:WINDOWSSystem32wuauclt.exe . If you find it anywhere else then you should be suspicious for sure.
You'll want to keep an eye on this google search for any known viruses.