Well, it will make a difference through LAN since all traffic will be going through the router(Unless he has a switch)
Cat6 is a lot faster(10x by what I see, I can't remember the real number) and is rated from 550mbs, whereas cat5e is 350mbs.
I'm trying to find the differences between cat6 and cat6e but I can't find them.

 

The Gig switch/router will help for streaming music/video from the closet PC to the entertainment PC

 

I'd be using a gigabit switch.

 

Okay, well then the router won't matter if its gigabit or not.

 

Great

Now is there that much of a difference with gigabit?

 

Yes. Gigabit Ethernet transmits at a gigabit per second. Fast Ethernet is 10 to 100 mb a second

So since you're having a media server for your home network, it will make a huge difference. I'm not sure about the differences in price. I should look into that. I'm making a server/home media server/DVR soon(I'll be using Myth)

 

i'm sure most people only have 1 subnet in their homes. in that case, the traffic is all switched and not routed.

you might be thinking 4-port linksys router. but it's not a 4 port router, it's a router with a built-in 4 port switch. routing doesnt take into effect until you try reaching a different subnet

 

I realize that but if you only have a 10/100 switch or router, you won't get gigabit speeds.

 

gee really captain obvious?

 

STFU. I don't think Joe got what I meant.