|If you have the windows XP key (usually on a sticker on the case somewhere) and can check what it is... - and note if it says OEM as part of the characters given. If so then you can download an ISO for an OEM, burn it to to cd/dvd (XP will usually fit on a cd) and then use "your" OEM key to install it. If you go for the ISO get the version that has sp-3 included.|
If (and unlikely in this case) the installation is a retail version then you download a retail version of the ISO; burn to a cd/dvd and boot up with that - using "your" key for the installation. If "your" key doesn't have OEM included within it, then it's a fair be that yoi=u have a retail installation; but that is highly unlikely.
Again go for the sp-3 version.
The ISO can be download - for free - at the site posted by riider (#9) in this CN post:
What I'm not sure about is whether or not the versions of XP offered there are retail or OEM. Usually you cannot use an OEM key with a retail disk and visa versa...
But first have a browse at these two (hp) links; the second discusses which key to press for a recovery partition approach i depends on which OS version etc.you may have...; and also ordering the disk set. The first (and top of the list) may be of general interest too; and includes the actual hp link to the second site I've posted below.