Windows 7 must appeal to geeks--or else
news.cnet.com
news.cnet.com
"the geeks want better security, more customization, and full compatibility."
Assuming geeks are highly tech savvy, living at the bleeding edge, is full compatibility such a big issue? It also seems to be incompatible with security, if you're going to support legacy code you're going to be left with legacy vulnerabilities as well.
I've no good suggestions for killer features but I'll know them when I see them.
#2 is tough. Really tough. But I would start with customization - make sure everything can be changed.