Shop Vac as a dust collector

Currenty in my ever evolving shop I am using a 12 gallon shop vac as my only means of dust collection. It works on some machines pretty well: my sander, miter saw, Kreg Jig, and router table. I cant hook it up to my table saw yet or my skil saw which I have been using to rip panels of MDF the past couple of days (which is working pretty well!).
I cant hook it up to my table saw because the dust port is larger than the hose on the vac, probably 4" when the hose is probably 2 1/2"-3". I checked at my local Lowes but I was unable to find a converter that would work. I havent really tried to hard to jerry-rig some sort of setup. My Dewalt skill saw just doesnt have anywhere to attatch a vaccuumm hose.
A bigger problem is the fact that the filter on the shop vac gets clogged and the vacuums suction power deminishes. I have been looking online at the Onieda Dust Deputy system. Basically its a 5 gallon bucket with a funnel on top that removes the particles and suposedly most of the dust that clogs up the filter.
The Dust Deputy
I have read reviews online and people have given the Dust Deputy pretty good remarks, so I guess I will give it a try. If it works it should be worth the money!