My Raspberry Pi just get delivered this week, so here are some notes for future me if I ever need to use my Rpi as a media centre again.
|Raspbmc in action|
I'm not really gonna use my Rpi mainly as a media centre since it would be wasteful for me, however I'll try it this time so I can get some idea on how easy or difficult it can be.
So for TL;DR:
1. Setup Raspbmc - Very easy
2. Getting TP-LINK WN725N V2 nano usb WiFi module working with Raspbmc* - Easy (relative to your Googling skill)
3. Configure XBMC - Very Easy
Edit: *Finally, support for 8188EU chipsets already added into the Raspbmc kernel after latest hotfix update ~ http://www.raspbmc.com/2013/10/raspbmc-hotfix/