My computer is currently configured like this: hard drive 1 (sda1) is WinXP, hard drive 2 (sda1) is Win Vista, and hard drive 3 (sda3) is PCLOS 2009. the Windows bootloader is on sda1 and sees WinXP and Win Vista. I originally loaded PCLOS 2009 with Sda 1 and 2 disconnected, so it doesn't know Windows is there. If I install PCLOS 2010 with the two Windows drives connected, and install Grub on sda1 (where the Windows bootloader is now), will I have a Grub menu with 3 choices (WinXP, Vista and PCLOS)? Or, will Windows be goofed up? I have important stuff on the Vista drive. By the way, both Windows drives are formatted NTFS, and I intend to use EXT4 for PCLOS.
I would have suggested that you set the BIOS to boot from the third HDD and install PCLOS on that and Grub to its MBR.
That would have kept PCLOS completely independent of the Win bootloader, while allowing you to boot Win from the Grub boot option page.
In case of failure of the PCLOS disk you could then reset your BIOS to boot from the first HDD and be back to the original setup.
IMO, it is a much better option for anyone with two or more HDDs.
Just as a matter of interest I would point out that your disks are not numbered sda1, sda2, sda3 but most likely
sda, sdb, sdc and the first partition on each would be sda1, sdb1, sdc1.
That info is added for anyone else reading this thread and wondering about the hard disk numbering