I'm not an expert, but the question of whether or not they are still good to drink is fairly easy: look for wine stains or drips coming from the cork. If the bottles were laid on their side, the wine inside 'seals' against the cork, thereby keeping the cork from drying out and cracking and allowing the wine to seep out. Once this happens, wine goes bad rather quickly. BEFORE you open the bottles, check on a wine forum to see if these are even worth anything or not to a collector. If they are, get rid of them (unless you really want to drink 35-year-old wine???) through a sale or such... If you just have to see for yourself if this wine is any good, go ahead and open a bottle, wait a few seconds, then gently sniff the open bottle. If it's bad, you'll know instantly as it will smell much like vinegar or sour grapes. If it smells okay, pour a small amount into a clear wine glass and examine the wine for clarity - the wine should be very clear, not cloudy, and there should be absolutely nothing floating around in it. Take another sniff of it while in the wine glass and see how it smells.
Anyhow...those are just my pointers...but I'd honestly see if a collector would want to buy them from you first...but be prepared to answer questions about how it was stored: dark/light room, stored on it's side or upright, cork stained/leaking, etc.