Tony, there are two main types of port, the kind aged in bottle, called ruby port, and the kind aged in barrel, called tawny.
Colheita is a vintage tawny, so it's a tiny percentage of the very best stuff. 1997 was a great year.
Sorry if you knew all of the above, but the main point is that tawnies are released when they're ready to drink.
It will certainly last for quite a while, but it's not going to get better. I have enjoyed Feist wines in the past but have not tasted this particular one. If you want to know how good it is, my advice is to crack that one open and test drive it.
re: Chris Weber
I opened it up last night and thought it was quite good. It was at the end of the night so my tastebuds were a bit fatigued (a fancy way of saying I was a bit hammered). We put out some chocolate truffles and cheeses to go with and everyone seemed to enjoy it. Thanks for the info.