I don't know how cold is cold where you are but for a 5 mile commute, I would wear a pair of thermal tights or tapered fleece pants. The North Face makes a few good pair that can be found at Backcountry.com or Altrec.com.

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DISH is how we do it.

I have some Specialized tights that are awesome, soft micro fleece lined, articulated at the knees, and wind-stopper on the front. The only thing I don't like is the small runs a little short in the leg, but a tall pair of merino socks bridges the gap nicely :)

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Trying to fight gravity on a planet that insists

+1 on tights. wind-stopper is a plus, although that can certainly add to the cost. depends on how big your wallet is :)

I have a pair of PI fleece lined cycling tights that are toasty warm. They don't have windstopper front, but the fabric is really dense and they work well.

Check REI and REI Outlet.com

I have a pair of Gore tights with no chamois, that are windstopper fabric on the front and otherwise not too crazy thick elsewhere. They are also articulated at the knees. When it's really cruddy outside, these are great because the wind doesn't touch you but you also don't overheat.

I second the Specialized fleece knickers - I love mine. They're pretty much what I wear all winter, with varying sock lengths.