I don't think you need anything special in the router. It's the NAS enclosure that has to deal with the computers. The router just forwards traffic between different ports, it doesn't know or care what is the data being transmitted. (This is a slight simplification in that there is such a thing as high priority traffic).

Also, you can simply buy another switch (those are quite inexpensive now) and connect to your router and get more ports to connect to network-ready printers, computers, NAS enclosures, etc.

A few words about NAS enclosures. I have a Netgear Storage Central SC101 and it stinks. Special software has to be installed in order for a computer to see the drives. It's slow, and it doesn't seem to like one of my drives. Oh, and it uses a proprietary data format so if you stick a hard drive from your computer into it, it gets wiped first and you see an empty drive when you connect to it. Of course, it was only around $50 so I guess I shouldn't have expected too much. It's disappointing because I am quite happy with my Netgear AP/router/switch.

To xyzzy, do you have any 802.11n equipped mobile devices? If not, do you plan to acquire them in the near future? If not, I think you should hold off on the draft-N AP purchase. They are still relatively expensive while 802.11g ones are fairly inexpensive. You can probably buy an 802.11g now, wait until you actually have 802.11n mobile devices, then upgrade to an 802.11n AP and spend roughly the same money as buying a draft-N AP now. Just my opinion of course.