You MUST store you works of art carefully.  I recommend  UPPER MIDWEST CONSERVATION ASSOCIATION  for acid free and general curatorial storage advice.  

As to those of my products that would serve,  this depends on the size and nature of the artwork.  If -for example- you collect smallish paintings, drawings, and just general things on paper,  (up to about 14 inches by 30 inches), you might consider some of the larger -flatter drawer cases in my ARCHITECTURAL  CASEWORK  line. These have the advantage of providing a lot of very secure, very convenient, and very economical storage for your collection.  Particularly if you don't mind doing a little work on your own private art-museum.

Display Cases for Art:

Putting a framed picture in a display case might seem to be gilding the lily, but then again, if the frame is as old and/or as valuable as the art, perhaps it's not all that silly after all to protect the whole thing in it's own display case.  

If you have larger artwork, say statuary, you might do well to have a  look at doll display cases, or look into a custom plastic cover, or -.  There are often plastic fabricators in most cities.  You can find such in the phonebook under Plastic, Fabricators.  They are not cheap, but the have lots of experience dealing with people who may not be accustomed to specifying dimensions and materials etc. for a fabrication project.  

Additionally, check out Designing Your Own Custom Display Case for insight on the nuts and bolts.  Might be helpful to read Hiring Carpenters, and Other Useful Things -if only to pick up on some of the lingo that this sort of people use.  

Dick Blick is simply the best place to buy art supplies.  And if you have a artist wan'a-be in your life, (and you are real cheap), their catalogue is a great gift all by itself.  But the best thing about Dick Blick is what it does to your tongue when you say it over and over  -Dick Blick Dick Blick Dick Blick Dick Blick Dick Blick Dick Blick....  see what I mean?

Want to know what a given painting might be worth?  Or just want to look at some nice art?  Art Facts has almost one & a half million auction references cum prices and 300 thousand+ pictures.

Check out Art Collecting.  This is a great site to get you started in this rewarding pursuit and has lots of excellent (and serious) advice on preserving art.