Always regularly back up your data, including favorites/bookmarks, address books and anything else that you don't want to lose. I always back up important stuff at least twice. If possible, back up your entire system. Your computer could crash any time--treat your data as such.
Also, make sure you know where your system and/or recovery, applications, and device driver (like video, sound, printer, scanner, etc.) disks are. Some device drivers may be on your recovery and/or system CD. When possible, make backup copies.