I discovered a must install KB for Hyper-V BizTalk installations if you are using NLB today. 

I'm setting up the lab for our BizTalk 2009 performance boot camp next week.  We're comparing the performance of common Orchestration scenarios and optimizations that we've discovered on the R2 platform on 2009 physical and 2009 running in a Hyper-V environment.  The results of this will be published in the BizTalk 2009 Performance Optimization Guide and the BizTalk 2009 Hyper-V Guide (see the previous versions http://technet.microsoft.com/en-us/library/cc558617.aspx and http://technet.microsoft.com/en-us/library/cc768518.aspx.

Because we're using WCF receive locations I set up NLB on the Hyper-V boxes.  Everytime I logged onto the boxes and try and install BizTalk 2009 the boxes would Blue Screen of Death. 

After much troubleshooting that KB953828 resolves the issue.

http://support.microsoft.com/kb/953828/en-us