Installing Windows is pretty self-explanatory. The only thing you may not know anything about if you have never done it before is partitioning. When it gets to that point either just make one large NTFS partition or creat just one and leave a little amount of space left for a second partition. Then when you are done installing Windows you can create a second partition to use as storage. This way when you reinstall Windows all you ahve to do is reformat the first partition and you still have all the stuff that was on your storage partition. It also may help with fragmentation.
As for the actual installation these guides may help.
Windows XP Home
Windows XP Pro
Once you are done installing Windows you will need to install drivers and update Windows. The first thing you should do is install SP2 if it is not already installed. It may actually be best to slipstream SP2
before installing Windows to prevent problems. You can use something like
AutoStreamer would be a good idea.
The next thing to do is install your motherboards chipset drives, vide drivers, sound drivers and NIC drivers. It is best to do it in that order. It is actually a good idea to download all the drivers you may need and burn them to a CD
before you install Windows. This way you do not have to browse the internet searching for them. it is also important to use the most up-to-date drivers. That is why it is best to download them from the manufacturers site. If you have a PC that you did not build yourself such as a Dell you can just go to their site and download the drivers.
After those drivers are installed if a device is not working properly you may also need the drivers for that. A perfect example is a printer which will need drivers. Just as before download the drivers from the manufacturers site.
After all the drivers and everything are installed and everything is working properly you should go to Windows Update and download all the updates.
Ftaer this make sure to take security seriously so something like this does not happen again.