Buffalo isn't bad, but be careful of "factory provided". Its like "factory applied" thermal paste on a heat sink, its always better off to remove and put on the real thing. And since its free...its a win win. But yea, Linksys, Buffalo and Asus are the three main brands you hear about on the forums. Asus is a good brand, but they haven't yet jumped in with both feet into the networking world.
BTW, where did you buy the 4500? If it falls under the manufacture warranty, can they except exchange through a local D-link approved vendor?