I just checked the HP web site, and found that, for one particular model of HP minitower quad core Windows 7 computer, factory disks cost less than $17 with shipping. I happen to have, and use, one HP Windows 7 computer, and got the factory disks because the ones that can be made "at home" will be on recordable media, which may become forgetful before I might need to do a full factory restore after a C drive failure trashed the C drive recovery partition. A restore to factory, on the HP computer I have will reformat the C drive, thereby doing in all user-installed software and all user data.

Sadly I needed the entire Internal Hard Disk 1 terabyte Drive.