I highly recommend doing the following. Put your operating system (xp media center) CD into the cd tray and reboot the pc. Hopefully the pc will ask you to hit any button shortly after you restart it (watch the screen as you will have a 5 second window). It will run through some prompts and simple menus. Afterwards you are going to want to delete the partition and format (do not use quick) the hard drive. You cannot break anything here, the worst that you could do is waste your time messing with a pc (learning). If it is possible use FAT32 for the process use it, but if that isn't an option use whatever else it gives you. Once formatting is complete it will save some files to the hard drive, and then reboot. Then it will begin the installation process, most of the process is automatic and the window options are very simple to understand and take very little technical understanding to complete. The whole process may take a few hours (or more depending on your hard drive), so there is a bit of time that you can let the bird fly. After you have completed the process you will need to reinstall all of your drivers for your computer (video card, sound card, ethernet et cetera) and as you said you have all of the CD's you need to reinstall all of those things, but be sure that you already have all of that prior to sinking the ship because once she goes down, you cannot simply hit escape and pretend it never happend. If you have any other questions feel free to ask! Good luck!
