Had a friend call who said his xp to win2k lan had cacked. Used to work and now crawls. For edification of anyone else with this issue here is the solution.
Bill,
Finally solved my problem. There were two issues. The first had to do with security signatures. See this link to see what needs to be done. It seems that when critical patches are applied to Windows they are treated differently for 2000 and XP. These were alluded to in the link you sent but not explained well. This link both explains how to fix the signature problem but also has a link to how to fix the IP packet ACK problem (this was the root cause for my problems). There are links at the bottom of the page (MORE INFORMATION) that shows how to fix this problem. Note that the fix for 2000 is completely different from the fix for XP. The articles are not very clear on how to identify the GUID for the local area interface (the only one that you need to fix). if you do a "ipconfig" you will see the IP address of the NIC, just look in each GUID till you find it's address and apply the fix there. The machine needs to reboot for the changes to take effect. My transfer went from 15.4 hours to 2.1 minutes to transfer a 1 Gig file (Eeeek!). A very substantial difference.

The link: [link|http://support.microsoft.com/default.aspx?scid=kb;en-us;321169&Product=winxp|http://support.micro...169&Product=winxp]
thanx,
bill