We use the last generation iMac 27" i5 with the ATI 4850 video card. We experienced zero problems and we literally run SU 10 hours a day with 20-30 different plugins and 100mb site models. In fact I'll be heading to grad school in a month and I plan to buy the same computer for my extensive SU use.

Caveat: I have a Thinkpad t60 with ATI Firegl card and it has all sorts of weird display issues. Its my understanding that ATI and SU problems where mostly limited to the past.

The exterior have an incredible sense of realism, did you use Vue or Vray for these? Also are all the plants of your own creation?

IMHO the interior images lack that dynamic lighting needed to make it pop. Maybe turn on some kitchen lights or consider different perspectives.

Otherwise, your rendering skill is starting to match up with your modeling talents. Keep it up, I am sure you will become a master of all that is SU.