I would buy a MIX rig instead for serveral reasons. To begin with, two of those DSP cards are as powerful as one of the MIX cards.
MIX cards can be found for as little as $50 or so on ebay, and interfaces around the same.
For the second thing, in a PTIII system you are limited to 32 mono tracks or 16 stereo tracks. On the MIX systems, it's double that.
The MIX system can also handle 24bit audio, which the PTIII can not.
Here you have a MIX Core and Farm card with a 5-node TDM cable so you can expand the system with more Farm cards as you move along.
http://www.ebay.com.au/itm/Digidesign-Mix-Core-And-Farm-Cards-For-Protools-W-ribbon-Cable-/171365339035?pt=LH_DefaultDomain_0&hash=item27e62b8f9b&_uhb=1This rig has the same amount of processing power as the system you posted.
Together with this interface, it makes for a great system.
http://www.ebay.com.au/itm/Avid-Digidesign-888-Audio-MC-Avid-I-O-Interface-/271367770983?pt=AU_Pro_Audio&hash=item3f2ec79367&_uhb=1All the software, including ALOT of plugins can be found here on Mac OS 9 Lives
Read my post about buying a MIX system to get some insight to how it all is built:
http://macos9lives.com/smforum/index.php?topic=435.0To sum it up; the MIX system is twice the processing power and twice the track count for the same amount of money or less.
As for the learning curve, I think it's worth it. But it's up to you as an individual to make that decition.
I work in big studios from time to time, where Pro Tools still has a strong hold, so learning it has really been worth the while.
PT is easy. Two windows for everything you need to do
-Knezzen