[sassan]

Generally portraits are much better with a Full Frame by virtue of versatilely it gives to you for crop etc.
Though you may like to look at 1Ds line of products, unless you are very fortunate / have a bank to sponsor you / Your firm is exceptionally wealthy / You are one one very $#@&^!* rich guy etc, you would prefer to go for 5D.
With new 5D Mk II on the horizon, the older very capable original 5D prices are to fall like avalanche. Of course if you can go for New 5DII then you have the opportunity of shooting HD video clips by the same camera and excellent L lenses you have some right now that is a big benefit but most of times, costumers go two independent professionals for still and video shooting so its upto you deciding what works best for you. Used 1Ds Mk II is a good option if you find a good deal (And there are plenty out there). Surprising to me most of 1Ds owners, have saved their gears all the time (As evident by the low auctuation count of second hand ones in the market today) and seems that back up 20D was their main house power!!! I am still seeing maximum number of pros doing their bulk work with 20D so why are you not satisfied with your 40D is another question to me.
You need 1D Mk III if you have too many Sport event coverage. Though some call this body the best ballanced machine Canon ever built.

My suggestions:
- Buy an older good 5D or 5D mk II if you can afford it. Keep in mind that the second one will keep the price for a will longer and first is a lot easier achievable these days.
- Sell your 17-40 L F/4 and buy 16-35 L F/2.8 instead
- Definitely keep your 28-70 f2.8 and 70-200 f4. 70-200 F/2.8IS is attractive but you will have to pay alot for your disc surgeries if you want to run around a lot with it, and your other F/2.8s cover the low light.
- Buy a 50mm F 1.4 or 85mm 1.8 (Both non-L) or Sigma 105mm Macro, but I prefer the first for those especial light conditions that you are garantied to run into often.
- Sell your 40D, buy 2 20D. At about $300 each these days, you can't go wrong with this fantastic camera as your main / emergency body (Same battery, EFs capability in additon to EF etc etc).