carseats for preschooler and baby

I went and had a look at ther Radian XT SL today, and love it! So think we are sold on that for the baby. The thing is I now feel bad cos my 2;9year old's carseat is just a bit of a cheapy cos to be honest I hadn't read a lot about car seats before having her and just thought if they passed safety standards they were all equal IYGWIM.... So, now I feel like we should replace hers - she is 90cms, about 14 kg. Is it worth getting her a radian too? or any other suggestions?

Also has anyone used the Radian from birth? or do we really need a capsule too? I hate getting the capsules in and out of the car so even when I used them with my other two, most the time I just left it in the car rather than getting it in and out...

Freckle - I am having the same dilemma. I've decided to get a Radian for my eldest (about the same size as your child) but it makes my other car seat look like an ice cream container so I think we might get one for our baby too. If only they had been around 3 years ago..