Nikon D3100 or Canon T1i for SLR Beginner

Hi all!
I'm looking to buy my first SLR camera and am strongly considering the two models in my title. I have had a chance to look at each and I really don't have a specific preference from just holding/playing with them. I plan on taking pictures of my young kiddos both indoors and outdoors, as well as their sporting events (soccer, basketball, football games). I'd like for the camera to be speedy in continuous shooting mode (makes me sway towards the Canon) and I really, really want a camera that will work well indoors in low light (makes me sway towards the Nikon). I do understand part of that is the lens that I put on it. I love the video feature on both (won't be used a lot, but enough that I want it)...but really like that the Nikon has AF in the video mode. I've also looked into the Pentax Kx which seems to be a reasonable choice as well, but not as many available accessories. Overall, I think I'm leaning towards the Nikon...with my one reservation being that it only shoots 3 fps as opposed to the faster Canon and Pentax. Can someone please advise me which of these might fit my needs better...unless there is a different option that I haven't mentioned. Thank you so so much for any advice!
Timberly