The CATIA V5 pre-requisites are MD2, GPS, FMS, and FMD.
If you don´t have one FLUENT fails.
Other reason could be the license, it runs with FLEXLM.
Wich is the error message when you try to run it????
It seems to be a problem with flexlm,
do you have more than one software using services from flexlm?
Try to start the fluent service and reread the license file in the LMTOOLS(if you have more thann one service in flexlm stop all before doing it)
It runs under xp, i think your only problem is the license server, may be the version of flexlm or simply flexlm doesn`t get the license file.
wich is the flexlm´s version???