Hi Katrina,
I have windows XP with service pack 3 on my small ACER Netbook, which is permanently attached to my KN7000 and linked to my home network. Both Song Manager and Jukebox 5 work OK on this Netbook. I can't vouch for TechManager since I don't use it, but I see no reason why that program should not work OK, when SP3 is installed.
Should you experience problems with SP3 / TechManager, you can always uninstall SP3 by following the procedures detailed here : http://support.microsoft.com/kb/950249