Install the harddrive in your computer and make sure it is made active and formated.

Now download the boot manager program of your choice and install it as per instructions of the program.

Reboot and choose the active drive that you just installed...insert the installation cd and reboot following the prompts and it should install very simply.

I use BootIt NG from ($35 us)

TeraByte Unlimited :: Boot Manager :: Partition Manager :: Drive Image :: Disk Copy :: Drive Wipe :: Hard Drive Utilities

There are some good reports concerning GAG which is a free program in which i am testing for myself and seems to be working perfectly!

Download GAG 4.9 - free boot manager. Allows boot of up to 9 different operating systems - Softpedia

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Using a boot manager other than what comes within windows is the easiest and best way to dual boot. There are no special registry tricks to perform or any editing of the Master Boot record or anything.
The boot manager controls the boot operating prior to loading the operating system and then hides the boot files of all other operating systems so as to protect the integrity of the operating system...All data files can be shared between the operating systems just as if they were on a network.

In dual booting with windows boot manager if there is a problem you usually lose bootability with all operating syatems....this doesn't happen with using third party boot managers as each operating sytem retains it's own boot files....