I installed ISE 10.1 but cannot access the IP Catalog when I select a V5FXT component. However, if I select a V5 LXT device, the IP catalog is displayed as expected.
The EDK cores for Virtex-5 FXT are still in Early Access state. If you go to Edit -> Preferences and check the "Display EARLY ACCESS IP Cores" option in the IP Catalog and IP config Dialog tab, you will see the IP cores in the IP catalog.
This problem has been fixed in the latest 10.1 Service Pack available at:
The first service pack containing the fix is 10.1 Service Pack 2.