Possible Duplicate:
Can you help me with my software licensing question?
I have migration question:
Can I migrate Microsoft Terminal Server Licenses from Win2003 to Win2008?
Can I migrate Citrix XenApp 5 Standard (Presentation Server 4.5) licenses from Win2003 to Win2008?
If not do I have purchase new licenses or can I just upgrade them?
You ought to be able to use the XenApp Licenses on 2008 without problems, but remember that the licenses are tied to the hostname of the license server. If you are deploying a new license server, you will have to have them re-issued. Otherwise, you should be able to just join the new machines to the farm.
The TS licenses will probably have to be bought new unless you have current SA on them.