Um... I have a Windows 7 PC with a Wacom drawing pad, M$ Office, Adobe Reader and high-speed wired networking. Other than the fact that you can take it with you and it runs on battery, are there any specific advantages to a Win7 tablet?

The point I'd make here is that the eDGe is not and has never tried to be a full tablet PC, and arguably, doesn't even try hard to be a full netbook. Sure, if you strip away the e-ink and dual screen because they're features you'd never use, you're better off getting a traditional Android or Windows tablet. Beefier processor, better graphics, more peripherals, more standard PC software, and if you know where to look, lower pricetag.
As Sarah mentioned, though, there are plenty of actions in an average daily workflow for which, if you have them, the second screen, the quick-and-dirty drawing interface, and the ability to go for extended time using only the low-power e-ink screen are game-changers.