If you don't want to go though the trouble of installing a boot manager like Grub (not that hard if you follow Dencorso's instructions), just know that your MOBO allows you to choose which disk you want to boot from. All you have to do is press F11 during startup. So, if your main system will be 98, you can just set the Boot priority to IDE in your BIOS. If you ever need to switch to Linux, all you have to do is press F11 at startup and select the SATA drive. This way, your disks would be fully independent and, if for some reason, one of them fails, you'll still be able to boot the other one.