Ay-yi-yi. Time to set the record straight here.
The only tickets that would not still be good are the old Length of Stay passes (they expired on the day of checkout) or any tickets that were bought with an expiration date printed on them. That's pretty self-explanatory. Other than that, the old tickets are still good.
The tickets bought prior to 1996 are very easy to tell what's left on them. Just look at how many stamps are on them. Example: If you have a 5 day pass and there is only 4 stamps on it, you have an unused day.

Your friend will have to take that old pass to any Guest Relations window to have it converted (for free!) to one of the current magnetic strip tickets. They will give your friend back a current ticket with exactly the same unused admissions as the old one had. Once they have converted those old tickets to the magnetic strip ones, those tickets can be used at any of the four major theme parks. It does not matter what parks were in existence when the original ticket was bought. There is NO extra charge of any kind whatsoever.
Now, if any of the tickets were purchased from 1996 on, they are already the magnetic strip tickets. You cannot tell by looking at these tickets what remains unused and you cannot call. The only way your friend can find out is to bring them to WDW and have them scanned. This can be done at your Disney resort front desk or Guest Services, or at any Guest Relations window at WDW.
Here's the most important thing to tell her.
DO NOT UPGRADE THE OLD TICKETS!! JUST USE THEM!! The Disney CM's might try to get her to upgrade the old tickets to a newer, longer ticket. What they actually do is give you a dollar credit based on what your friend paid for the ticket when she bought it and apply it to a new ticket sold at 2003 prices. She will pay a lot of extra money needlessly to do this.
It's great discovering 10 year old tickets that still can be used. She'll save a bundle. I hope she has enough left over days to cover her whole trip!
