ok this is a rough outline.
go into your bios and ensure your boot order is set to,
1.CD Drive
2.Hardrive
now insert your windows xp bootbale c.d save bios changes and reboot computer,
when it displays press any key to boot from c.d well press any key lol,
ok now the setup will start wait 1-3 mins until it needs input something along the lines of recovery console = r and install XP enter, press enter.
press F8 to accept the license agreement
if you had a previous XP installation it will ask you if you want to repair it so press esc on that one, ( if it doesnt ask dont worry)
you should next see your hardrive in a list of places to install XP choose your drive and hit enter,
now the next screen should be formatting options i always choose ntfs quick,
now wait 5-15 mins and i believe from memory the next screen that will need input is your keyboard and OS language options,
cant remember exact buttons here but make sure if your from uk then change the default keyboard layout otherwise you will spend a few hours finding your @ key.
next it will ask for your XP serial no, insert this.
then click next and TBH ive forgotten the rest i think pretty much its self explanatory from now on you shud b fine