Finding Operating System for 2007 Macbook

You get Mac OS X 10.6 Snow Leopard for 19 USD from the Apple Online Store and do a clean install.

To create a Clean Install (formerly known as Erase & Install) of Mac OS X 10.6 Snow Leopard (the 19 USD Upgrade DVD is a fully working retail version of Mac OS X and does not need a prior installation of Mac OS X on the Mac), follow one of the following guides:

• Short version: Clean Install of OS X 10.6 Snow Leopard
• Long version: Mac OS X v10.6 Snow Leopard: How to Erase and Install

​

 

You can order replacement discs for your model by calling Apple (800-767-2775 in the US).
You can also buy a retail copy of Snow Leopard.
The maximum OS you can install is 10.7.5.
It will not support Mountain Lion.

You can find specs on all Apple products:

• By visiting EveryMac.com
• By using Mactracker
• By entering your serial number here to find specs for your model.

 

I would download osx lion off of the mac app store. Do this to mac a bootable usb.

http://www.pcmag.com/article2/0,2817,2389178,00.asp

Go to utilities > disc utility from installer, select your hard drive; not the partition, ensure erase is selected from top menu, (this step and the next is optional for security) click security options, select 35 pass overwrite, click erase.

 

35 pass erase? Really? With an 80 GB HDD it would take at least 15 hours (lucky to have such a small HDD in this case, imagine doing that to a 1 TB HDD - 8 days at least), if the write speed would be constantly 50 MB/s (which it is not).
And a a simple ZERO OUT will suffice protecting data from being not be able to be recovered by data recovery software (awaiting a spam post in the next twelve months, do not disappoint me my fellow spammers).

DiskWiping – One Pass is Enough

 

OS X Lion is no longer in the Mac App Store. You have to call Apple, pay $20 and get a special redeem code and you can download it.

That said, the OPs machine only has 1GB RAM, so, you cannot install Lion as it wants 2GB. Additionally, you cannot install Lion direct onto a 2007 Machine, you have to upgrade from or on top of Snow Leopard... With additional hardware, there are ways around the above, but with just the machine, the OP will need a Snow Leopard disc.