Misdee, dd1 was/is a bit like this - we've just had her school report and though we don't have SATs here we have national assessments and she has passed the level she is expected to attain at age 12 (she is 8!).
The main thing I would say is to be guided by her and her interests. At your dd2's age, dd1 was obsessed by colouring in, so I got a huge roll of paper from Ikea and drew lots of intricate pictures for us to colour in together. I would read her lots and lots of stories and be at pains to answer all her questions. We used to make up stories a lot (even now she and dd2 clamour for made-up stories when we go for a walk).
She learnt to read in nursery and would spend hours poring over books until she mastered every word. Again, we encouraged her to read as much as she wanted and gave her a wide variety of books. I work in a library now and bring home a new book for her most days (again, her reading is advanced, she reads mostly the 10-14 age group stuff).
Like your dd2 her motor skills are not great (though not quite like your dd2) - she struggled learning to cut out (and is still very poor at it compared to dd2), teaching her to ride a bike was a nightmare so bad that I still haven't faced teaching dd2
(!), and right now I am trying to teach her to wash her hair by herself (AAAAAAAAAAAAARRRRRRRRRRRRRRGGGGGGGGGGGGHHHHHHHHHHH). Her intellectual skills are certainly more developed!
And lastly I would echo Anniemac - dd2 is also very bright but very different and needs a lot of encouragement and praise - fortunately for us the teacher (they are in the same class, tiny school) is very aware of not comparing them and of championing their own achievements.
Lizs gives lots of sensible advice too. I agree that you should aim for breadth of experience and development rather than pushing her to achieve above her level - we encourage dd1 to (for example read plenty of books aimed at her own age as well as older stuff - it would be so easy to push her on and have her miss out so much.
HTH!