It's all just another way of getting more money from people who dont know better, like all PC so called improvements.
When I changed my router to a gigabit one, plus 2 switches, i thought I would use the same cat-5 cable, eveything worked perfectly, it was faster than my original 10/100 router, but you will never get gigabit.
All PC's and the PS3 has gigabit network connections.
Then I heard that I should re cable my network with cat-6 cable, so off to CPC to get a reel of cable and conectors, not cheap ether.
Did it speed up my network, did it bollox, no increase at all, I use a program from Cisco to monitor the bandwidth speed each PC using, and nothing changed.
Removing QOS did speed things up a little though. And sending files from Vista to Vista is faster then Vista to XP or XP to Vista.
The only thing I found that dramatically improved network performance was when I got rid of all the cjeap natsy network cards and used good quality ones, which I did before converting to gigabit.