I won't step into the 'whether a house is an investment' argument, but I don't think it's a bad idea to sell some or all to help fund a home purchase. I'm considering doing the same thing within the next year.
While I love collecting as much as the next guy, in the end, it's just cardboard. A home is an investment in your family and your life. I'd take a home over a stack of cardboard any day, unless the stack came from the Black Swamp...