It is best to reference the release notes for known hardware and software compatibility information.
Release Notes for Cisco Unified Business/Department Attendant Console Release v8.0.0.5
http://www.cisco.com/en/US/docs/voice_ip_comm/cucmac/arc/cubdacrn8005.pdf
Based on these release notes alone I would say CUBAC v8.0.0.5 is expected to work on Windows 2008 R1 (32 bit). It is the nature of documentation to only list what is expected to work, everything else is an unkown and may or may not work. I would not recommend deploying any unkown configuration, such as Windows 2008 R2, in to a mission critical environment.
