I know a lot of guys are pushing the win7 install. Openelec was an absolute breeze for me and the install now takes me about 15 minutes including hardware install.
On holiday, so can't really type up a quick start guide.
The life hacker guides are pretty good.
Make sure your media (tv shows, movies) are media server ready. See life hacker. In general the life hacker guides good.
With regards to accessing the server over WiFi, there are a few things you need to do first. Make sure everything is enabled under setup, services. Username is xbmc, password leave blank. Make sure you have a static IP. Easiest way is under the openelec settings menu e.g. 192.168.0.199 (depends on your router ip range, the last digits are the ones you're setting, you can see current up under system, system info)
In Windows ensure your sharing settings are enabled. Hit the Windows key and type network sharing.
Then you should be able to go to run, and type \\192.168.0.198 hit enter and browse to the server
Sabnzbd suite is under the addons menu which is on an unofficial repository on the latest version. You have to manually install the repository from a zip file. Google about it. Then there are lots of guides on setup. Your nzb indexes/sites, search this forum. Same for news servers and their addresses. You'll want a paid server as backup (I use a once off astraweb account)
On an advanced level you can get the watched status to sync across installations using the addon trakt. Which is easier than dealing with sql.
My Swype is not used to this much text. So that's it for now.