I was using a point and shoot when my daughter was born and soon realised that it isn't fast enough and then got a D40 with 18-55mm kit lens which served my purpose until I wanted good bokeh (at a budget). Sold off the D40 June this year and got the D80 with 18-135mm kit plus AF 50mm 1.8D and it has been GREAT! I also got a SB600 flash and the set up is good to go. When I want nice bokeh, I slap on the 50mm and use the 18-135 particularly outdoors when she's playing in the pool. So, speaking from my own experience, I felt for the amount to get the Sigma 30mm 1.4 lens, I thought it would be better to get the D80 (D90 not out yet then in June) plus AF 50mm 1.8D. Now that the D90 is out, perhaps you could consider that instead plus you could take videos of your baby as he/she grows (which I do with my trusty Fujifilm F31fd).