Hi Gurus,
My main purpose of the camera is to shoot great quality pictures of my 2 month old, and also pictures when we go out to scenic places etc. Also, i need to be able to shoot some nice quality HD Videos.(for about 5-10 mins)Now Since my budget is not more than $1100, here are my options:

1) Nikon D90 with 18-55 mm lens ( sells for around 1100)
2) Canon EOS Rebel T1i (18-55mm lens + 55-200mm lens)(Sells for around 1000 in Best Buy)
3) Nikon D90 Body Only + Sigma 18-200mm f3.5-6.3 DC

I found reviews that Nikon D90 performs better than Canon t1i but again , Nikon is a couple hundred dollars more than canon. Nikon just gives 5 min videos, but with Canon T1i we can shoot 18 min videos in 720p. With canon bundle , i will get an additional 55-200 lens but is it a pain to change lenses around all the time.?

So please advise if its ok to buy Nikon D90 body only and use a Sigma lens with it , so that i have the advantage of both wide range pictures at home and also Telephoto pictures when outside.