|If you have a SATA HDD, read this "how-to":|
If you have an older IDE HDD, the installation is pretty straight forward. Just boot off the XP disc, delete ALL current partitions (all data will be lost), create at least 2 new partitions (one for the OS, the other for Storage), format them as NTFS, then go ahead & install XP.
You we need to find XP compatible drivers for the motherboard chipset, video, sound, network, etc. Even if there are drivers on the disc, they are at least 10 yrs old. After that's done, install SP3, IE8, & all the other Windows Updates. Then install a lightweight anti-virus program such as AVAST, AVG, or Microsoft Security Essentials, then continue with the installation of the rest of your software.