I too ran into the dreaded isearch.exe, desktop search, sysupd.dll C:\WINDOWS\isrvs problem.
I tried McAfee Anti-Spyware, then Spybot S& D, then Ewido Security Suite.
Ewido was much better than all these others, but was very time consuming.
Once the items were isolated, it seemed that they could really not be eliminated.
I then scanned with SpySweeper from webroot.com
It got all of the files.
Cleaned everything off and no isearch in the taskbar now.
We are Windows XP, and I had McAfee Anti-Virus on the system, but it doesn't stand a chance against this desktop demon.
Things are running real fast and very smoothly now.