I'm still not a wink connosieur.
By the way the "Cab" is a Robert Mondavi wine. Is that a decent Calif. Cab?

Take it to someone who is an expert. I doubt it is good.

1999 would typically be young for a good quality Cab. Even an inexpensive or lower quality Cab would still be drinkable at that age if stored properly. Even the best wine, if it kept at room temperature all this time, would probably be garbage (wine needs to be kept cool, ideally between 50 and 60 degrees). A wine's ability to get better or at least stay okay with age depends alot on the weather of that year where it was made. Tell us the name of the wine and we can tell you how well it would taste today.

The vintage is the year the wine was harvested, and some years are better for wine than others. Most wine is better after a period of time in the bottle, not less good. And the quality of the wine depends on where it was grown and how it was made and how it was treated after it was bottled. 1999 therefore has little relevance, except to indicate that the wine has had a nice period of aging in the bottle, so it should be perfectly fine.

I mean, a 1999 bottle of Cabernet made by a vintner on an estate in France is going to be better than a 1999 bottle of Cab I made in my bathtub, no?

this bottle depending on the vintage and if stored properly should be ready to drink in 2009. Age reduces the tannins in the wine making it smoother