Help me spend money!

Right, so, I've currently got a Cannondale MTB, a 2011 Trek 1.5 and am getting a fixie / s/speed for commuting at the end of May (probably a Felt Brougham). The plan is to stop using my Trek for "everyday" and use the fixie.

The question now is do I a) Get a new £1k road bike when my BTW scheme ends in September. I like the look of the Cannondale CAAD 8 w/ 105 for £1049 or

b) spend money on upgrading the components on my Trek such as brakes, groupset and wheels (and anything else I fancy)?

I might struggle to spend £1k on upgrading components on my Trek and will do it bit by bit (unless my LBS is 'flexible' on its approach to the BTW scheme Wink )

I suppose the question is - which is likely to give me the better bike after spending £1k?