Selling old Imac and have ? on cleaning HDD.

[nicolbr]

I just purchased a new Imac and am looking to sell my old 17 white intel Imac. I have all the updated software(snow leopard, Ilife 09). I was going to sell on craigslist to stranger but now looks like a family member will buy. What is the best way to delete my info but being able to keep 3rd party programs and music on the machine. Also if I just choose to do a complete install instead do I use the snow leopard disc or the disc that came with the machine which it had Tiger on it. Any help will be appreciated.
Thanks

[Hellhammer]

If you don't have an external HD, create a partition with Disk Utility and copy music and apps you need to there and then wipe the HD by booting from SL disk and selecting Disk Utility from Menu Bar and erasing the HD (you may want to do secure erase if you had something personal there) and after that, reinstalling OS X from the same SL disk. Then move the stuff from other partition to the new one and repartition it back to one partition

[nicolbr]

If i have an external I can copy programs and music to it and transfer them back after cleaning and reinstalling on internal HDD? thanks again for the response

[Hellhammer]

If i have an external I can copy programs and music to it and transfer them back after cleaning and reinstalling on internal HDD? thanks again for the response

Yeah, though some apps may not like and needs reinstalling (big apps like Photoshop)