Not to get into an "argument"
, but I've never had a problem with 64-bit systems (either *nix or Windows) with BING. I don't think that BING knows/cares whether the systems that are installed on partitions are 32 or 64 bit...
Wait - it may be that there is something in the MBR or EMBR that is 32 or 64 bit sensitive (I don't know)? But then again pretty much all of the systems I work on for the last 5+ years are basically all 64 bits.