Believe it or not - a few of my readers are having a hard time with this. it's ok. I was there, many times before. Fortunately, Backtrack 5 is relatively easy to install to your hard drive and make bootable. I remember before Backtrack there was a linux distribution called P.H.L.A.K. Acronym for "Professional Hackers Linux Assault Kit". anyway, it was nearly impossible during the first few releases to install to the hard disk. you had to manually partition the drive yourself, configure the boot loader yourself and then hope that you don't lose any data creating the swap and Ext partitions. Backtrack 5 does it all automatically. I have a few pictures (taken with a smartphone) to help guide the way for you.
I highly advise installing backtrack 5 to the hard drive. the CD loader takes waaay to long to get anything done and you really don't need to use a whole lot of hard drive space.
First thing you need is a computer running backtrack 5 on a live DVD
 Then all you have to do is click the Install Backtrack icon

 Starting here:
go through each step
Step 1, 2 and 3 are Language, Time zone and keyboard layout.
After that, it can be a bit tricky re-sizing and partitioning the drive
What you want to do here is click "Install them side by side, choosing between them each startup"
what this will do is keep your windows or other OS partitions but resize them, making available disc space to install backtrack 5 on. at the bottom of the screen there is a slider - on the right side slide the slider to desired size of your backtrack partition. i chose 40.1gb. That's plenty for me. unless you're going to be keeping a lot of files and saving music and images, you really shouldn't need more than 30gb's.
click forward, then continue. the setup will then install backtrack after partitioning the drive
Keep in mind, the new boot loader will have BT5 as first  option by default. just hit the down arrow to select your other os.
All questions are welcome to email