Foxy:

The problem with your strategy is in the early game. The units that you choose are both fairly weak untill they are fully upgraded. Pretty much any form of rush would take you out.

To improve, I would do the following. Use the Arbiter as your leader. He is possibly the best early defence unit, and also does great mid and late game.

You should also go for fast Wraiths. If you have ~6 out by 6 minutes, you will have a) 6 Shelided Wraiths b) Even more early defence and c) a pretty good economy, if you're only getting them at 6 minutes. From the out, build some more Wraiths and your other units, and attack as soon as your ready. An advantage that I see is that your army choice can be massed fairly quickly, so you should have a decent shot.

Your strategy isn't fool-proof, but it could net you some low-medium level wins, especially if you incorporate my suggestions. Also, you may want to try this in 3v3, as those games tend to make it to late-game more.

Hope this all helps, good luck!

Thanks for the advice.  This idea doesn't seem to weak against PoR rushes though.  I just tested it out in 1v1 Standard.  I easily deflected several waves and made them quit.  Rushers don't want to waste time playing mid and late game if they can win four others in the same amount of time, so I wasn't surprised.  As long as I apply two Shield Generators to my base the shield easily holds out while I produce an army of Ghosts and EHGs.  I also had the time to upgrade Cleansing, a major help in defeating other PoRs who tend to research the other half of their prophets skills first, in order to get two plasma cannons.

The ghosts took out the enemy PoR and Jackals easily enough, and the EHGs handled the Hunters.  I reserved my Cleansing Beam for the enemy EGHs and PoR.