Was there any reason given for not using Linksys?
Personally I love my BEFSR41, got nothing but good things to say about it. It's never once "locked up" on me like you'll hear about some routers doing and I put mine though a lot.
Now... having said that, I actually downloaded the pdf manual for the D-Link DI-604 and after looking through it I'll admit that it has several nice features lacking from my Linksys plus the filtering looks much more powerfull!
As much as I like my Linksys I'd have to say that the D-Link would be the better buy. (Although I can't comment on the robustness of the D-Link so you might want to find someone who has used it.)
One other thing I noticed about the two routers you mentioned is that the NetGear is a wireless router yet the D-Link is not... Do you want wireless or not? It would make more sense to compare either two wireless routers or two wired routers.
I've worked with the MR814 a
little bit and it is not nearly as feature rich as the D-Link you are considering. Then again it is wireless and includes different features...
If I were you I'd decide if you want wireless or not and then choose two similar routers to get an opinion on.