I have know lag as a problem between your pc and server and many other people on that same server working together. Yes that might be true that windows IP stack being a like default setting for windows XP or Vista to be slower than it could. But you can change that by editing the regesitry if you know what your doing or have a program do it for you. To help speed network performance. I remember a site that would help speed up your internet connection all it did was check your system over and change windows some windows registry keys. But that default setting MS provides is the best option for all diffrent things you might use your network card for. But I have never seen anyone try to sell a piece of hardware like this. I would figure lag would be more software related and how your network is built at home. Ya the guy that uses all high dollar Cisco stuff might have a better network than a guy using Linsys or Dlink hardware stuff. I don't see how this card could help if you still have that other hardware stuff in your home network.