I tested this out myself because I couldn't find any information on it, and I'm posting the results here:
Hardware:
MacBook (13-inch, Late 2009) with SSD, 8GB memory. The CPU is 2.26GHz Intel Core 2 Duo processor.
Configuration:
I installed Media Center 20 on Mac (10.8 I think?) and tried streaming a 720x480 30fps dvd rip to my TV using the general profile (NTSC dvd/mpeg2?). I also tried streaming some ALACs.
Results:
Video: I hit 110% CPU usage for the first 4 seconds, then it stabilized to 40%. Skipping around was decent enough. The CPU didn't spike.
Audio: I also played some ALACs converted to mp3 high bandwidth and they took about 10% CPU.I didn't bother testing FLAC or MP3.
Conclusion:
This hardware will work perfectly for a MC host for work, home, and a DLNA server for the living room. I'm not a videophile and don't even have any bluray rips, but for standard DVD rips and music it looks like it will work perfectly.