I switched to gigabit and was surprised at the increase of speed. The office is wired with 5e cable so there was no problem a 500 mB file transferred in about 30 seconds.
Wired is definately the best way to go, but it may not always be practical if you do not own the location (sometimes a problem with non profits) or cannot do it yourself or for low cost. It is often simple and I have wired both of my offices by myself.
Wireless N may work if there are reasons not to wire. Of course G networks CAN work fine and often do, but he is having a problem, thus all of the above makes more sense.
I agree I do not feel the server will make a big difference.
