Cervelo Soloist or Trek Madone 4.5?

I'm new to the sport, but I ride tons so I want to get myself a really good bike, but not a specialised TT bike because most of my training rides are on the way to and from work (but I don't use panniers) which is a 40k round trip that I often extend to make it 30 - 40k one way in the mornings.  So a road bike converted for aero bars would do the trick.

I recently discovered the Cervelo Soloist and I think it's a super cool bike that probably will fit all my needs (I always want to go faster!).  I've read lots of glowing reviews about it from a number of sources - and these reviews have also made me less certain about wanting just any old road bike to convert for tris because of how they explained the different geometry of the Soloist. 

But, being a comparison shopper and an over zealous researcher, I started looking at comparables.  The guy at the Trek store tells me that the Trek Madone 4.5 is the bike for me.  But his job is to sell me a Trek bike so I want to hear about it from someone who isn't actually trying to sell me the bike, but just likes it (or doesn't as the case may be).

So what can people tell me about these two bikes?  Anyone else use them?  And what about Cannondale bikes?  I think it was the Cannondale 800 that was suggested to me as another comparable.

I'm a woman, 5'4", average build (i.e. not an especially long or short torso, legs, arms).

Thanks!