OS X fresh install + new hard drive problems

bdizzle11

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May 19, 2011
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Apparently no one goes into the Mac os x forums so Im going to retry here :sarcastic:
I am currently in the process of upgrading my sisters old macbook (late 2009) 13", just a basic ram and hard drive upgrade. After formatting the hard drive I placed it in and put in the old leopard disc to reinstall that before purchasing and downloading the snow leopard upgrade. Everything was smooth sailing until I began the install, it almost immediately gave me an error, "Install failed, mac os x could not be installe don your computer. Unknown error blah blah blah".
I read up on what this means and did the checks that I found. My hard drive is correctly formatted, it is "verified", the computer recognizes it. But it just wont install. I did try to run the repair hard drive thing from disk utility and it gives me "the disk "main" could not be unmounted". I could not find a fix to this online. When I just hit verify though it gives me no errors and says it appears to be ok.
What is the problem with installing Leopard from this disk onto the hard drive? Any and all advice is greatly appreciated. Im just about fed up with MACs at this point. Thanks!