Yes, I am very behind in updates. It hasn't been a problem until I got a new printer. Now I can't get the print drive to run, because my oporating system is too old. I tied downloading the 10.6 but it can't run because I don't have 10.5. Do you now if this download is still available anywhere?
Upgrades to the next version of OS X are not available for download, they have to be purchased.
Look on eBay or Amazon, but make sure you get the black retail disk of Leopard OS 10.5.x and not some's discarded updater.