Attached Link: http://www.discreet.com/products/cleaner_ez/

Sounds like your AVIs are uncompressed. Coincedently, Online last nigh,t I walked my brother through compressing a 428MB uncompressed AVI into an 877K MOV with NO quality loss. I use Quicktime Pro and the ON2 codec, but as I understand it, Poser (on a PC)only allows AVIs. QT Pro will compress into numerous formats including AVI, I think it costs 30 bucks or so. Checkout Discreet's EZCleaner. I do belive it's FREE. Link attached.