AJLynn

To be fair, they're pretty much equally expandable - the Mac has a nicer system for adding hard drives but the Dell can take almost anything the Mac can, and there are a bunch of aftermarket video cards the Dell can take that the Mac won't run in OSX without some hacking.

One nice thing the Mac will do that the Dell won't is run Elgato products - they make HDTV tuners and the software to deal with them, and they allow most useful edits and file format conversions while ignoring the broadcast flag restrictions, which it turns out are voluntary though Microsoft would never tell you that.