I have a Windows 7 HTPC connected to my TV via HDMI.  My media is stored on my unRAID and my iMac is on the other side of the living room.  They're all connected via ethernet.  I've been using XBMC on the Mac and Windows, but I find it would be much quicker and easier to just use my Mac to access the files and send to the TV.  I know I could run a DVI and Audio cables across the room, but I'd rather use the Windows PC, since it's already hooked up.

  I thought I could use Remote Desktop Connection to configure the mac as one display and the TV as a second, it won't let me on a remote connection.  Any ideas how I can do this? 

Take a look at one of the VNC implementations - VNC clients are few and far between on the Mac, but two to try are Jollys Fast VNC or Chicken of the VNC

Have you tried XBMC Live?  It is a lot faster than XBMC on top of Win7.  I just don't see any reason to involve the iMac at all when you've got a full-fledged HTPC.

I'll look into XBMC Live.  I wanted to control from the imac because I sit right by my imac when I'm watching movies and it would just be convenient to use the same keyboard & mouse to control the xbmc.  Right now I have the little lenovo controller, which is great, but it's small and not really ergonomic.

Checkout Synergy.  It will let you use the mouse and keyboard of your Macbook to control your Windows HTPC.  It's basically a virtual KVM.  Check it out at http://synergy-foss.org/

will do

or just get a  rosewell remote for $25 from newegg to control your HTPC and be done with it.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16880101002&cm_re=rosewell_remote_controll-_-80-101-002-_-Product

 

-=Jason=-

Start following the HTTP-API, JSON, AJAX, and PHP threads in the XBMC forum.  There are now several versions of control system implementations that are web based ergo OS independent.  You should be able to select one with some reasearch that will run on Safari on the MAC and give you complete control of XBMC running on the PC.  A lot of ad hoc developers are looking at and playing in this arena.  Look at the development sub forum in the XBMC forums. I have built onefor the Philips Pronto that I am playing with, a fellow named sWORDs (his handle) is working on a very complete one for that platform.  Others are doing it for web browsers as I stated.