With Windows, I have this whole ritual for keeping things clean that include these free utilities

* Spybot. Keep immunizations up for adware, spyware and use its Tools to fix the registry of bad entries, cleanup startup groups of shovelware
* Zonealarm. take the updates to this firewall and make sure to disable the native XP firewall
* PerfectDisk. This isn't freeware, but it is a great disk defragger that you have to run regularly
* Norton Ghost. Again not freeware, but does an incremental backup of your hard drive.

On the Mac, I don't have a similar routine, but "Macmerc.com":http://www.macmerc.com/articles/Power_User_Monday_Tip_of_the_Week/255 does have a good list but of course after I ran Yasu, it corrupted my entire MacBook Air boot drive, so that upon boot, it failed with a spinning wheel and the Apple logo. Not good! Am going through a full rebuild now. Thank goodness that the low level "DVD Sharing for OS X Install":http://www.maciverse.com/reinstalling-os-x-on-macbook-air.html works. I guess I get what I want, a clean MacBook Air!

MacMerc.com: Routine Maintenance

Required Materials
1. Disk Utility (Included with Mac OS X)
2. Keychain Access (Included with Mac OS X 10.3 and higher) or Keychain First Aid (For Mac OS X 10.2, Free)
3. Yasu ($3.50) at "Jim Mitchell":http://jimmitchell.org/projects/yasu/ 4. Preferential Treatment (Free) at "Jonn8":http://www.jonn8.com/html/pt.html 5. BootCD (Free) 6. DiskWarrior ($79.95)
7. ClamXAv

Here is his procedure:

# Create a Bootable CD so that you can run things like Disk Utility offline and tackle the hard drive. Unfortunately, this utility only works up to 10.2 (Jaguar) and is borken for 10.3 (Panther), 10.4 (Tiger) and 10.5 (Leopard)
# Restart your Mac so everything works well
# Verify or repair your keychain. This happens to me quite a bit, you can get a corrupt keychain. With 10.3 or higher, goto Spotlight and find _Keychain Access_ and choose Keychain Access/Keychain First Aid and run Verify and if it bad, then click Repair.
# Goto Spotlight and search for _Disk Utility_ and use it to verify. This fixed permissions that prevent access to thing.
# Preferential Treatment looks corrupt plists, these are preference lists used by applications. If they are corrupt, the application might crash
# Run Yasu with everything selected, this deletes lots of cached data which can get corrupted. The system builds it all back again automatically as you use your computer, but corruptions can happen. Be really careful on this one, appears to Corrupt OS X 10.5.5!
# Update ClamXAv virus definition files
# Make sure Firefox has adblock and flashblock on.