vs 2005 from 32bit to 64bit

I have a few projects that were created with vs2005 and have package and deployed to several machines, 32 bit operating system.  The run great, I am now trying to deploy them to a 64 bit operating system.  The do not work and I get errors.  I was looking and found where I have to specify that I am running a 64 in the package builder.  I have done that and now I'm getting warnings of  "Possible problem detected while building assembly 'envoyrpts': Referenced assembly 'mscorlib.dll' targets a different processor" and "Possible problem detected while building assembly 'envoyrpts': Referenced assembly 'System.Data.dll' targets a different processor" and "Possible problem detected while building assembly 'envoyrpts': Referenced assembly 'System.Web.dll' targets a different processor".  Can anyone help me out on these error in order to correct them?  Also why would it make a difference when they ran fine on 32bit and now will not run on 64bit.  Thanks for the help in advance.