>I am trying to implement the FTP Service Class written by Robert Abram.
>I am able to "Put" files up onto my target FTP site when my OS is Windows 2000, but not using Windows XP.

The file directory standard has probably changed in XP, thus, maybe that class doesn't check for that. I'm not aware of anything different in XP in regards to that. However, as for that class, you can try to contact the owner of the class directly to see if he is already aware of such situation. For reference, here's a small article I wrote about it:

http://www.levelextreme.com/Magazine/November2001/Page20.asp