Getting rid of identifying info?

I am selling my Macbook. They are too expensive to repair, too expensive to replace, and getting help from the Mac store is too time-consuming. So I'm going back to Windows.
So I am preparing it to sell. I.e. getting rid of all personal identifying info. My questions are:
Is it best to re-install the system, and will that get rid of old stuff?
Even though I have gotten rid of email addresses in Airport, it still refers to it and downloads my emails. I don't want that to happen. So what do I do to get rid of it?
Is there anything else I should know?
Would reformatting and reinstalling the system make sure that it's clean?

Thanks for reading. I hope you'll help me.

 

http://mac.majorgeeks.com/download6065.html
I'm not a MAC user but I was always told that even though you restore a hard drive, unless it is erased several times data can still be recovered. I looked on Major geeks software for mac and this program indicates that it erases your drive several time. Take a look at it make sure it can work on your system and also make sure that, if you use it you can still reload your original software, before you run it.
I'm quite sure someone else will come through with more and advice on this

 

I do not know much about MACs but i found this,it may help.

http://macosx.com/forums/mac-os-x-system-mac-software/303745-howto-wipe-internal-hard-disk.html

 

Well thank you both for replying. Even though you're not Mac users I appreciate you helping me. I thought I'd posted in the Mac Forum. Another reason to go back to Windows eh? I will use that permanent eraser program and I'll re-install the system. I hope that cuts the link to my email account in Airport. I need to put it on ebay soon.
Once again Windows geeks to the rescue!