Trend Micro HijackThis
Full user review
"been using for a while now."
a must install on clean systems, create a whitelist and know when things change.
easy to use if you know what's going on.
there is no magically process information list so you have to do your research online or in forums.
not for the average computer user, really powerful, can easily mess things up if you think the log is bad, it's not, it's a log: ignore [whitelist] all the good processes.