Decisions. New hardware for LAN party

I have been hosting LAN parties for about 4 years now and I was recently thinking of upgrading my network to gigabit. I've been tossing around a few different ideas on what hardware to get and what configuration to use, but I'd like to get some outside opinions to play devils advocate for me. I host my parties in my home and the turn out is usually somewhere between 10 - 25 people.

So far I've decided on a D-Link DGL-4300 http://games.dlink.com/products/?pid=370 for my wireless router. I would like to implement 2 16-port switches ( one for each room that my guests set up in). I guess my main question would be whether or not the router (which has 4 gigabit ethernet ports) would be sufficient for my core or should I get an additional smaller 4-8 port switch and uplink that to my router. My concern is whether the router will be as efficient at handling the traffic as a switch, or at least comparable.

Any input would be appreciated. I'm no expert with this so feel free to bash all my ideas to pieces if you think they suck

I'm not sure if this is posted in the correct area. Sorry if it isn't.

Thanks for the input. That's probably what I'll end up doing. No sense in wasting money on an extra switch if I don't need it!