Re: What do I do?
Mikaboshi,
While some things have changed and character creation point costs are different, the actual *gameplay* has changed very little between 5th and 6th edition (and for that matter, little between 1st edition and 6th edition).
I recommend running with the books you have. If your interest (and the interest of your players) grows, consider going to 6th edition as your financial situation allows.
In short, enjoy what you have, and if you have the interest and finances, convert to 6th.
Good luck!