Hi there DonnieDoonerMe and welcome to geeks to go
What I would reccomend is instead of doing a format and re-installation I would do a full repair.
To do this load your cd into your cd drive and then boot off the cd, some pc's automatically detect booting off the cd, if yours does not when it boots up keep pressing F11 and a menu may appear and will ask you which hard drive, optical drive to boot, please note that this does vary from pc to pc as other ones I have seen use F8 although this is normally used to enter safe mode etc...
When your disk loads up to the welcome screen press enter and it will search for previous installations, when that has finished it will give you the chance to repair the installation, when you have told it to repair it will start repairing your installation and it will then reboot.
Upon reboot it will look like it is doing a full installation (don't worry) you will then be asked to choose all your regional and language settings and so on, then you will need to enter your licence key, once all this is done it will once again restart. When your system has restarted it will begin to load into windows xp and you can begin to setup your computer, if it asks to create a new account under NO
circumstances create one as you will lose all your data, never ever create a new account if you are repairing an installation. When all that is done you will be able to login to your system
I would also like to add to BudMarLeY reply although I never believe in different partitions these can be very useful indeed, especially when stuff like this happens as what you can do is have your operating system on one partition and all your backups such as photos on another so incase you do need to format one day you can always have a backup of your important data, if you would like to partition your drive but are unsure please ask and we will be more than happy to help you
Once again welcome to geeks to go