As for Macs being PC's I think it's fair to say that, in this context, most people are reading PC as Windows PC. As the underlying hardware for Windows, Mac OS X and many forms of Unix is x86 based these days it can't be distinguished by the underlying hardware so if you want to merge Mac and PC hardware then you'd also have to lose Open Source as it's all running on pretty much the same kit.

I'd suggest keeping Mac and PC hardware boards separate and maybe re-naming PC software as Windows Software for clarity and keeping Open Source for non Windows or OS X software. Merge the Internet and Networking boards. Programming stays as is as it's a completely different focus from the other Software boards.
Not sure about Sports. I normally think of that going with In The News (like it does on the TV).