If you have XP Home Edition, it is likely the manufacturer did not supply
the XP Backup applet though you might check your system's documentation,
whatever the manufacturer supplied to see if they did install some sort of
backup program. If not, there are several third party apps that can handle
this function. The backup app that is normally supplied with XP is quite
limited and in fact is a "lite" version of the following application for
which there is a free trial downloadable, fully functional version you can
test for 30 days before buying, it's called Backup MyPC:
http://www.stompinc.com/index.phtml?stp
Personally, I use the above program but another program that seems to be
highly regarded is ZipBackup for Windows which also has a 30 day free trial:
http://www.zipbackup.com
As to the other function, I believe you are referring to the "Repair
Install" feature and this requires an actual XP CD though if you check your
computer's documentation, the manufacturer may have provided you with such a
routine or function, check the computer's documentation or with their tech
support.
Note, whether or not an actual XP CD is supplied with a system is completely
at the option of the manufacturer. However, if they don't supply you with a
CD, they are required under their licensing agreement to provide you with
some means of recovery though this shouldn't be confused with a backup.
Other tools you might consider are imaging applications such as Norton
Ghost,
www.symantec.com or Partition Magic which is now owned by Symantec:
http://www.powerquest.com/
An image of your drive as it was after installing all your applications can
be useful in quickly recovering from a bad crash and is a useful supplement
to backups as well. However, imaging software creates rather large files so
unless you have a DVD burner or a backup computer or a secondary hard drive,
some form of media separate from your primary hard drive so it won't be lost
if your primary hard drive ceases to function your only choice would be to
place it on a separate partition on the same hard drive. In cases where you
don't lose the drive that's find but offers no protection if the hard drive
fails.