Thinking of erasing my Hard Drive, I need help

Hi there,
I need some help. I have the original Macbook, with the DVD Burner (Thank God I bought that) and I am running out of space on my 60GB HD. So here is the thing, on my computer I have about 20GB of photos and 20GB of Music, what I am planning on doing it burning that all onto DVD, erasing my Hard Drive, installing Leopard then adding it all back on again. I am really confused about my HD. I have seen that the "60GB HD" is actually only around 55GB so that still leaves me with 15GB left, then my Applications, 5GB, so then I have 10GB left, however my computer says that I only have 1.77GB left! So what is going on here! I am very confused and am not that smart when it comes to computers even though I have used Macs all my life. So any help on how to completely erase my HD would be greatly appreciated!
THANKS!

Well the 55GB is the actual amount you have. 60GB is just a marketing gimmick.

When you subtract 40GB for the pictures and music, you're left with about 15GB, as you noted. 5GB for Applications leaves you with 10GB. A typical OS X install is a couple of GB, easily accounting for 8GB, leaving you with a tad bit under 2GB. Looks like the math totally adds up.

I would highly suggest investing in an external drive to store your media file. They are dirt cheap now, you can get an 80GB drive for a measly $50.

You can also, of course, upgrade the internal hard drive of your Macbook. With 80GB drives starting at $55 and 120GB only $15 more, this is also a very economical way of solving your storage crisis.

External Drive

I picked up a iomega 350GB for about $150. It works great!