BizTalk Server can be installed on 32-bit as well as 64-bit Windows operating systems. You don’t need separate licenses for it. Moreover, both 32-bit as well as 64-bit executables can run simultaneously on windows x64. Simplest way to run 32-bit executable on 64-bit OS is to create a host instance by selecting “32-bit only” check box. To run 64-bit executable – assign the executable to run on host instance with unselected “32-bit only” check box and the host instance must be running on windows 64x machine.
It is obvious that in terms of performance, 64-bit CPU and Windows x64 would be a better choice against 32-bit. In addition to CPU processing you also get to utilize full 4GB of virtual memory.
Note – Standard Edition or Workgroup Edition BizTalk Server can only create 32-bit only Host
