As a disclaimer, I'm not a wedding photographer - but I did stay at a Holiday Inn Express last night (kidding)
Actually, I run a small lens and camera rental company in Pittsburgh and work with a lot of wedding photographers.
First off, do not under any circumstance by the current Tamron 70-200 lens. The autofocus is atrociously slow. If you want to buy a third-party 70-200mm lens buy the Sigma 70-200 f2.8 OS HSM (and make sure it's one with the Optical stabilization). While not in the same league as the newest Canon 70-200 f2.8 IS USM Mark II, the Sigma does a very respectable job and I have many satisfied clients who have rented it for wedding use. It can be found used for less than $1000.
Second, I wouldn't rent the 7D - get the 5D Mark II instead. Wedding photography involves low light and as much as I love the 7D (and I do, it's my favorite body to use even though I have the 5D Mark II and Mark III) it doesn't excel in low light.
As far as lenses, I'd recommend you rent the Tamron 24-70 f2.8 VC USD Lens to go with the Canon 5D Mark II. The Tamron offers VC (which the Canon 24-70's don't have) which can be very helpful in low light. It's also quite sharp.
My normal renters who use zooms usually get this package:
Canon 5D Mark II/Mark III
Tamron 24-70 f/2.8 VC USD
Canon 70-200 f/2.8 IS USM II
Canon Speedlite 580EX
If they've got some extra money, they'll add the Canon 16-35 f/2.8 IS USM.
You also might want to look into upgrading your 40D to a newer 18MP sensor as they do better in low light than the 40D (T2i, T3i, T4i, 60D, 7D)