From the look of it you've got a good mix of just about everything there to make use of any of the strengths of Isengard.
First off, what kind of pts value are you aiming for? 500pts is a good starting point normally.
The classic heavy infantry Isengard force tends to be 1/3 crossbows, with the rest a mix of pikes and shields (varies to preference I go for a 50/50 mix of pikes and shields)
You've got a lot of beserkers there, add them to the crossbows and you have enough to make a very elite force.
If you can get hold of Mauhur and 5 more scouts you'll have enough for a fast moving warband of marauders which have never let me down
You've got a good number of warg riders but getting hold of a mounted hero will really help them out, Sharku is a nice cheap 3 might captain for this role.
Vrasku is normally an Isengard favourite as his shooting abilities and 3 might are very handy.
The main thing missing from your list is an Uruk-hai Shaman as these really help with courage issues, ultimately you need a hero that can hold the force together when you break and need to start taking courage tests.
Saruman is good for this but cheaper options are Ugluk and the shaman.
Hope that helps
Edit: Just saw the title, for war of the ring I can only suggest buy models in packs of 8, lol sorry