Resetting a Mac password with or without a boot disk

Boot into single user mode: hold down Command (alt) -S on startup

Follow these steps:

http://osxdaily.com/2010/08/10/forgot-mac-password-how-to-reset-mac-password/

Restarting Directory Servcices from the Command Line: OS X

killall -HUP DirectoryService

DHCP will not authorize after a re-IP of the server

You must first unauthorize a DHCP server scope prior to re-IPing the server.  If you do not then you will be unable to re-authorize the scope after the re-IP.

If you have already re-IPed the server without first authorizing the scope open DHCP from Admin Tools, right-click on "DHCP" and go to "Manage Authorized Servers."  Find the old DHCP server name/IP and click on "Unauthorize."

Once you have removed the old DHCP server you can authorize the re-IPed server.

Mac Fonts

It is a good idea to remove all the fonts from ~/Library/Fonts and /Library/Fonts but leave /System/Library/Fonts alone.

Create a "My Fonts" folder, dump your fonts in there and activate when necessary.

Here are two good overviews of how the OSes handle fonts:

Leopard:  http://www.prepressure.com/fonts/basics/leopard_fonts

Snow Leopard:  http://www.prepressure.com/fonts/basics/snow-leopard-fonts