May I also suggest running a TCP optimizer. This one is very comprehensive. My recommended MTU is 1492 but using this tool I discovered that my actual maximum transmission unit is 1472. Adjusting this number, as well as allowing the other suggested changes, increased my performance so that I now achieve my ISP's advertised speed (up and down) within less than 5%. And this is wirelessly, through 3 walls, 50 feet away.
http://www.speedguide.net/tcpoptimizer.phpPerhaps I am naive, as I know that most of the folks that come here know a lot more about Networking than I do, but I never hear anyone speak of adjusting, or looking at, the hidden settings in Windows that can make or break your router's performance. Simple things such as looking at your DNS settings in the TCP/IP config. If the guys having crippling issues with connectivity are well aware of these settings and have already done everything possible, yes, you can tell me where to go.