^ Yes you can!
1. You can have several operating systems on one (or several Harddisks), with a Boot menu to choose from appearing at the start. The boot menu has to be on a separate partition if i remember right, and you have to partition the disk accordingly for it prior to installing the OSs.
It also depends on which OS you want to install, it is possible with Win and OS/2, or Win and Linux, or more, but after installing Windows you have to edit the boot file because the latter likes to overwrite other boot managers and menus, at least until Win7.
2. Regardless what is on the Harddisk, you can always boot from a CD/DVD (if the PC is eqipped with a Laser device) or even with a USB stick if the Bios menu offers that as an option.
This maybe some of the new UEFI thingies that have replaced the Bios.
"Secure Boot" to off, "launch csm" activated – should now be possible to boot from e.g. USB. The stick should be FAT 32 formatted.
Or .. does the "add new boot option" help?
