I need to install a new Windows XP on my brand new computer due to freezing up issues (suggested by customer service). They sent me the CD with the operating system and some other CD's. I started off the installation on the phone with CS and we hung up after we got things going. But my computer froze up during the installation and never really completed it (or so I think). I had to reboot the computer to get it working again. It boots to windows, but it is still freezing up.

Did the operating system get installed properly?
Can I restart the installation? Do I need to do anything prior to doing this?
Dumb question: What happens to the "faulty" operating system when the new one is put on?

Thanks!