Your friend should be able to find a local high-school kid who could help, or take to a local Best Buy and let the Geek Squad charge him for something that Google can help with for free. This really is pretty easy.
Is this friend older or disabled? If so, there may be local resources that can assist as well.
No, he's just very computer illiterate. I'm pretty experienced and even I didn't know what you were talking about. I mean, we are both freshman in high school, and my high school tends to have computer illiterate people.
Sounds like he is just going to re-install Windows. If that is the case, I wouldn't use XP for business use unless there is a compelling reason to keep XP. It is no longer being updated by Microsoft. Windows 7 or newer should be used.
During the installation process for Windows, you can remove existing partitions. Very simple process.