I had not seen this program mentioned here before, so I thought I'd bring it up. Sentinel http://www.runtimeware.com It's an integrity checker for home desktops that works with your existing Antivirus program. It scans your System32 directory by default (any any other directories you specify) creating a cryptographic hash of vulnerable file types (supports CRC32, MD4, MD5, & SHA-1) at Windows startup and directs your AV to scan specific files that have changed. Support for algorithms above CRC32 was added promptly by request, download and run the updater to get those options. You can enter settings for 2 AVs, and it includes a process monitor (shows child processes which you won't see in Task Manager) and a really nicely done viewer to see what's set to run at startup in your registry, and can scan for changes there on startup (on demand) & just on demand too.