So I've been having a recent love affair with ebay and just picked up a large quantity of evil folks. Predominately Isengard, so trying to throw a list together with what I have. Possible 500 pts:

Legion:
Uruk SHaman - 50
9 Uruk Hai Warriors sheild/sword - 90
9 Uruks with pike - 90
9 Orcs Shield/SPear - 63
9 Orcs Bow - 54

Raiders:
Sharku w/shield - 60
Warg Riders shield/throwing spear - 90

44 Units, 497 pts

What I have to play with:

Saruman (2!)
Ugluk
Lurtz (2!)
SHarku
Balista
2 Shamans
9 Orcs w/bows
36 Orc Warriors
2 Uruk Captains
5 Berzerkers
44 Uruk-Hais

Given that, what could you all suggest? I would like to keep it to what I have, but am willing to pick up the box of Warg Riders. Don't really know how effective they are, but I am a fan of a manouver unit like the wargs. Is it best to keep an Isengard force "pure," or would a vanilla RW or some such be a good asset as well?

The thing is that you need quantity over quality with a Isengard army.
I suggest using scouts combined with armoured warriors.

Really? I have found that a large pike-block of uruks can easily kill their points' worth.

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"War does not determine who is right, only who is left."
- Bertrand Russel

i have found tha hving 20+ pike men and shield men to form the front ranks with a few berserkers and captains spread throughout.

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When Isengard marches to war their is no stopping them.