"Archive and install" is an option in early versions of OS X installers. It moves some parts of the previous system to a folder called "Previous System" and installs the new OS.
There is also an option to presever user data and settings. See this document. http://support.apple.com/kb/ht1710
If you have 5 years' worth of photos and you do not want to lose them, then you NEED to have a backup. Hard drives can fail. Suddenly. Particularly on aging hardware. Computers can get stolen, set on fire or have drinks spilt over them.
If you do not have a backup, you should EXPECT to lose your files.
You should not need a store to make a copy of your files. Get an external drive, or use DVDs and move the files in the Finder. If you're using Leopard already, then you have Time Machine.
It would cost you less to follow benwiggy's excellent advice than to pay someone to copy the photos. You should buy an external hard drive and use it for regular backing up. Say less than $100 for a drive that will outlast your Mac. See this, for example: http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=293329 9&Sku=S130-8716
(only an example, not an endorsement)
You can get an external drive at any computer outlet, heck even Costco sells hard drives.