OP wrote above:
[[ Can I back it up to Drop Box? I'm trying to keep from buying another drive. I haven't upgraded the OS X 5.8 and it's now or never. ]]
Important question:
How valuable is the data on your computer?
What would you do if it was suddenly gone?
Backing up is simple.
Anyone can do it.
You have a MacBook, is that correct?
In that case, I'd suggest a portable USB3 drive, 1tb in size should be good.
These don't cost all that much.
You're still on OS 10.5.8, is this correct?
You could use an older version of SuperDuper to create a cloned backup.
You can find version 2.7.1 here:
http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html
(scroll towards bottom of page to see download link)
SuperDuper is FREE to download and it will create a full cloned backup FREE forever without registering.
There's an important reason to have a BOOTABLE backup.
If your MacBook internal drive dies, you will be "dead in the water" UNLESS you have an alternative source for booting.
A bootable clone can do this. Connect it and reboot, and you're running again.
All this is easier than you may be thinking.
Just try it!