I contacted NI and they told me that LabView 6i and 6.1 were both fully compatible with Windows XP and there would be no problems if we upgraded.
We upgraded one system as a test, and LabView worked fine, but the DaqCard 6024E fails with an IRQ Error. Tech support does not know what to do, and we have been down on this system for 2 weeks now. I'm glad we only upgraded the one system.
Pete