I know a lot of people who have recently switched from using plastic storage containers to all glass because of the concern of chemicals getting into their food.
I am not one of those people, mostly because I don't really like jumping on a bandwagon without knowing the details. I got curious, so I did a little googling.
I first found this article answering some FAQs about glass vs plastic containers. It more or less said to just make sure you know that your container is microwave safe.
Then, I saw a much more interesting Good Housekeeping article that actually tested different containers. 27 of the 31 different plastic containers tested contained no BPA. The 4 that did were then tested using actual food microwaved in them. Good news! None of the food contained BPA!
Finally, I found this mythbuster site that pretty much said that there's not a lot of truth to all of the hype.
This article was pro-glass, but more from an environmental standpoint. I don't throw my plastic containers away anyway. I reuse them just as much as I would glass.
This Canadian article had a good argument with some sound research backing it up. It was the best pro-glass article I read.
The vast majority of the research I saw basically said that the plastic containers nowadays are tested to ensure microwave safety. I'd throw out that old container from 1974 if I were you, but all of your "new" plastics should be fine.
Nevertheless, I do really like the new glass Boroseal line by Lock-n-Lock. They are a very thick, heavy glass with the same spillproof design, so you can go from the freezer to the microwave to the table in the same container.