Please bear with me. I know this has been covered before, but I want to get this right.
I have used Ubuntu 8.10 for a few days from the CD, and must say that I like what I see.
I want to install it to my hard drive.
Let me elaborate. I have two hard drives. One already has Vista, the other one is completely empty, and does not even show on the boot priority, but shows somehere in the BIOS. I want to install Ubuntu on the empty drive and not effect the Vista. I also want to choose which operating system on want on boot up.
what would be the best way of doing this?

Thanks in advance

There are many ways to do this.

The most straightforward is to simply install Ubuntu to drive #2. When it installs the bootloader, it will automatically detect the Windows system and set up the bootloader menu.

Another option is to tell the Ubuntu installer to put the bootloader on the SECOND drive. In this scenario, you would use the BIOS to select which to boot from.

The "booting" in my sig below might help also.

When you install select manual partition and edit your 2nd drive to be formated and used as root. I'll put up a byzanz video(gif) tutorial on http://nudepenguin.net tomorrow morning.

Before I go on, I want to understand the following.
When I finished my computer build, I went into the Boot Priority in the BIOS. It would only allow me to show either hard drive, but not both at the same time. I chose to show the larger one.
Should I now put the empty hard drive into the boot priority, and remove the one that has Vista on it? Sorry for the confusion.

When installing ubuntu have grub installed on first drive and it will pick up all your OSes and put them in your menu.lst on the /boot/grub folder which you can edit if needed by using sudo gedit /boot/grub/menu.lst

Sorry, but I am still confused about something.
I should put GRUB on the first hard drive.
What does that acutually mean? Since I have two SATA hard drives, anyone of them can be set to be the first.
Therefore, should I put GRUB on the Hard Drive that will contain Vista, or the one that will have Ubuntu?

Thanks in advance

No, do NOT put GRUB on the drive that has windows. It's only asking for trouble. The failsafe approach is:
- go into BIOS
- reverse disk order so that the empty drive becomes the boot drive
- install Ubuntu
- have it install its GRUB to the first (=its own) drive
- after booting Linux, you may need to perform a few small edits on your grub menu.lst to solve potential vista boot issues.

Thanks jaye, your help has been invaluable. I have been running Ubuntu 8.10 from the CD. So far I really like what I see. It recognized all the hardware that I tried, though I only tried my MP3 player, flash drive, and my Wifi card.
Now to business.
What kind of Potential Vista boot problems might develop?
If a problem develops, will I be able to back to BIOS and boot off the hard drive that has Vista?

Thanks again

If you don't want to change the mbr/boot info on the windows drive, disconnect it before you install Ubuntu on the second drive. You then install Ubuntu to that drive (second) and have it install Grub to the mbr of that (second) drive. When the installation is completed, I would suggest you try to re-boot to see if all went well before re-connecting your windows drive. At this point, you will not be able to boot windows even if you connect it's drive until you put an entry in the /boot/grub/menu.lst file of your second drive. The exact entry will depend upon your partition info from the first. Post the output of the command 'sudo fdisk -l' (lower case letter L) run as root on Ubuntu. You will be prompted for your user password. After you post this info, someone should be able to give you the correct entry for windows. Having done this, you will be able to boot both Ubuntu and windows with the second drive installed as long as it is set to first boot priority in the BIOS and will still be able to boot windows with the second drive removed.

Thanks Yancek:
One thing I am trying to understand. Why wont the Vista drive boot after the Ubuntu installation, being the fact that drive was disconnected, and therefore not affected? Trying to increase my knowledge base.

Windows tends to insist on sitting on the first drive; place it on another drive and it won't boot. Now there is a little GRUB trick called "mapping" that fools it into thinking that it really does reside on the first drive even when it does not. Keeps everyone happy, both GRUB and windows.
For a long time, GRUB was not smart enough to figure this out on itself so one had to do it manually - but recent distros like the latest Ubuntu may ship with an improved version that automatically take care of it. So, I don't know what will happen, maybe your vista will boot without a problem - but if it doesn't, then you know the reason and that it can be solved.
So why would you NOT keep things as they are and install GRUB on the first drive? That would work OK but you may run into trouble later. First of all because Installing GRUB one your windows drive makes it overwrite the windows bootloader. That is not necessarily a problem as people with only one drive have no other option. But it means that windows will not be able to boot anymore if for some reason you decide to remove GRUB and / or Ubuntu. There have been numerous posts on this board from puzzled people who were caught unawares. As long as you have the vista install disk, it can be solved - and quite easily too in most cases - but why bother if you can have your cake and eat it?
And the second, more important reason is that windows has always been extremely intolerant of other operating systems. If you install a service pack, there is a good chance that it will wreck either GRUB or itself if not both. With windows on your second drive, you can simply switch drives in BIOS for the update and rest assured that you won't get bitten.

Thanks jaye, it is becoming more undestandable. Exactly what should I do if Vista wont boot? Better to be have knowledge than fear.

Thanks again:

I will deal with this later in the day

Well, this is from my own /boot/grub/menu.lst:

The "root" line show that my XP is on the first partition of drive 2 (hd1,0). This would be a be a problem but it is solved by the two "map" lines, which "switch" drive 1 (hd0) and drive2 (hd1). This is not real switching, as you would do in BIOS, but it is good enough.

Jaye, one final question, I hope.

Why can't I install Ubuntu on its own drive without GRUB. I will then go into the BIOS and select which hard drive I want to be the first. Thanks for your patience in this matter.

Well, technically, you should be able to do without GRUB. You could use the live cd to boot ("boot from first disk" option). But let me assure you, going into BIOS or starting up a cd each time you boot gets pretty annoying pretty fast. I really don't see a reason why you shouldn't install it to the MBR of the Ubunut drive considering it leaves VISTA perfectly unaffected. Also, It's so easy to set up - you don't need to do anything, really, except click on "yes" or "OK".