Since I'm not sure it is worth bringing up on Meta as I'm hopped up on caffeine and not in a place to make good judgments:
4th Edition D&D has been torn down by Wizards of the Coast, since 5th Edition has been the real prime product they want you to buy for several years.
Several links from good answers on the site are to dead pages.
I've replaced those links with Wizards of the Coast's product listings on OneBookShelf (DriveThruRPG), on one answer, as well as adjusted wording here and there that I feel no longer applies (such as removing references to DDI).