If the app isn't x64 compatible, then the.msi file won't run. I've already come across software in the .msi format that will not run or install on an x64 system. Just because the OS can handle x86 or x64 software, doesn't mean the app in question is compatible. If it isn't compatible...it isn't going to work, simple as that. Are they behind the times? Absolutely, but it happens.