Shrouding

I've seen this done on Dell computers but I'm not sure how effective it is.

I have Silverstone AP-181's which use a grill to direct airflow in a narrower beam.

You could also try doing something like thishttp://www.sunbeamtech.com/PRODUCTS/Quarterback/Quarter...
to increase airflow in the middle of the case.

Okay, I'll check those sites out when I get home. Thanks for your help  

I've done a bit recently and it does seem to help, i'm pushing air into the pocket that the gpu draws from and pushing air into a pocket that the cpu cooler and exhaust fans then pull from.