I think it's looking like this at the moment
McLaren - Good, Mercedes/Ilmor seem to have got their heads around the 19k rev limit.
Renault - Cars have been suffering in grip in test's, seems the switch to the Bridgestone rubber may be the difficult bit for them.
Ferrari - Look quick, however they have moved to a Zero Keel design, and lengthened the wheel base, unsure on how reliably they are going to be at adjusting the car to the track/tyres, Kimi will be quick though.
BMW - They should be better than last year, nice stable team, with new people and techs coming on board.
Red Bull - If they can get their overheating issues sorted it should be a good package.
Toro Rosso - See above ;)
Honda - With a little luck 'Our Jenson' will have a quick / reliable package, they where the number 3 car at the end of last season.
Toyota - I wish they would do well, I have enough Toyota's and have worked for them so would like them to do well, they have a shed load of money, and some good resources. Problem? there based in the middle of Germany? move to the UK and they team will be a lot better.
Super Aguri - Last years Honda, so should be ok.
Spyker - Got a genius in the design department now, but he joined too late to make a difference to this years car, so expect next years car o be a bit better.
Williams - Nice Toyota engine, good sponsorship, well put together car. Should be quick
That said, winter testing is a bad place to 'guage' performance. Should be a good season!