Do I need to install the Boot Camp update in Mac OS X and Windows 7? I'm running Windows 7 on a Boot Camp partition on a 2010 Mac Pro running Lion. 

Every so often I'm prompted to download and install the latest update to the Boot Camp software under Windows but this doesn't ever seem to update the installed version of Boot Camp. I also get prompted to do this when in OS X. 

Should I update both or one of them? And if the latter, should I do one before the other?
I would update them both and I don't think you need to do one before the other. I have not had any problems updating one before the other and I manage large networks of Macs.