I agree with the other replys, that "practicing" a system
restore is not necessary. However, if you really want to
do it, remove the current hard drive, install a new one,
prepare it per hard drive manufactures intructions, then
pop in the restoration CD, and let it run.
However, such a restore will get you back to the day you
received your computer. All customizations will be lost.
All use programs will be lost. All user data files will
be lost.
By the way, if you ever have a hard drive crash or suffer
a serious virus attack, you can lose everything. So,
maybe your time woul be better spent practicing how to
save personal files and some settings on CD-R, ZIP,
external hard drive, etc
As for the original hard drive, if you attempt to place it
in another PC and boot from it, you will likely get (1) a
blue screen of death due to hardware incompatibilites
between the XP drivers and the current hardware, and (2) a
failure of XP activation. However, if you place it back
in the original PC, it shoud work fine.
The risk is doing all this is that you might damage some
hardware, either mechanically or by static disharge.
Also, the odds of accidentally loosing some other
connector within the PC is not zero.
Overall, I would recommend against "practicing" system
restore. It is somewhat akin to practicing CPR by first
stopping someone's heart.