Turn on computer. Press "Delete" key or "F(x)" <F1,F2,F3,etc.> to go to BIOS. [See
http://www.wiki.com for any Linux terminology that is not well understood]. In YOUR BIOS, set the First Boot Device to the one YOU will place YOUR Linux Distro in. I cheat, I change all of them to CD-ROM to install. Then after install, and before first boot, I make First Boot Device Hard Drive, Second Boot Device CD-ROM, and Third Boot Device Floppy Drive A. To install, add scsi support. Something like "doscsi" will work. E.G.,..."gentoo doscsi acpi=off", tells the kernel to boot gentoo and enable scsi drivers and turn off acpi at boot time. YOU may need to check for the Hardware Compatibility List to ensure all YOUR hardware will run each time YOU change YOUR Linux Distro.