Hi Oliver,
as I've replied already on the other thread: http://www.code4ward.net/main/Forums/...
I'm pretty sure that the issue you are experiencing is caused by RDP itself, so your options are limited. Since you are connecting to XP, I guess the behavior will be the same, regardless if you use Royal TS, mstsc.exe or any other product. Royal TS provides the feature to "type" the clipboard text, which is pretty unique and was originally implemented for Hyper-V sessions. Maybe this is sufficient, at least you get at least text from your local machine to the remote machine.
cheers