Well you do need to disable system restore before the sassre removal tool will work. Otherwise the fixed files are reinfected when you reboot.
http://groups.google.com/groups?q=Sasser+worm&hl=en&lr=&ie=UTF-8&selm=40a0d222.770937%40localhost.dot.net&rnum=2
FOllow these directions to fix, but first you MUST disable System Restore, to do so:
Click START>Control Panel>System>Performance>File System>Troubleshooting and check the "Disable System Restore" box.
Now when the tool is run the files are permanently deleted. If it returns on reboot, manually delete the registry files mentioned in the first link provided.
Don't forget to re-enable System Retore when done.
Good luck,
OM