Time Machine error code -43

[takastone]

I was trying to set up my Time Machine to an external hard drive. I didn't continue because it asked to "initialize" the hard drive which I had a lot of important things on.
I have another external hard drive I'd like to use but, my Time Machine has this error code of -43. What is this and how can I use my Time Machine on another external hard drive?

 

[Detrius]

If it's asking to initialize the drive, it's because it's not in HFS+ format. It's likely FAT32 which won't work.

Now, as far as the error message...

 

[takastone]

Time Machine Error Code

I went to applications for Time Machine. When I clicked on it the error code
-43 came up. I can't open it to go to Time Machine Preferences....
I don't have the back-up discs for my MacBook Pro.....(should you say to reinstall...purchased my laptop used) If I need to, am I able to purchase that particular application?
Is Time Machine on the disc Mac OS 10.5? I have that OS disc but I used it for my older PowerBook.... Will it work on a MacBook Pro?
Thanks for your help!