Shadows are all distorted

Hi All, I wonder if anyone can give me any advice how to fix my shadows. Ive adjusted pretty much everything I can having searched the forums for possible solutions. Ive got all objects on cast and receive shadows. Ive checked Player and adjusted project settings > Player to see if that makes a difference and it doesn't

Im wondering if my graphics card is just not up to it:

Im running Mac OS X Lion 10.7.5 Processor 2x2.66 Dual Core 4GB Memory Graphics NVDIA GeForce 7300 GT 256 MB

Im running the free (not Pro) edition of unity

I hope you can help!

thanks guys