I just took a look at the Google Desktop, (being fully aware of the security implications on public computers but this is my work workstation), and I really like it for searching my security logs.

If I wanted to find all the activity by a certain IP address in all the master log files I hold on this workstation, (several weeks), I would take forever using Windows Search. I installed it and told it only to index text files.... Man is it quick.... Saves a ton of time... I thoroughly recommend it for log searching.