I use TCP Optimizer on two different computers. One allows me to set the TCP window at 1027840 max (Marvell Yukon 88E8053 PCI-E) and the other allows me to go as high as 4111360 (LinkSys LNE100TX). Both network cards appear to have the same capabilities and both are set to auto-sense and use XP Home. What could account for the difference? This is not particular to any one version of TCP Optimizer either. Thanks.