Dxo labs test all camera sensors and lenses on the market. They rate the d3000 and 1100d the same with 62 points.
http://www.dxomark.com/index.php/Cameras/Compare-Camera-Sensors/Compare-cameras-side-by-side/%28appareil1%29/693|0/%28brand%29/Canon/%28appareil2%29/623|0/%28brand2%29/NikonThe canon performs slightly better at higher iso. I find the 1100d a bit plasticy. I would pop in a shop and have a feel of them both see what feels nicer, then walk back out and buy it online cos its cheaper!
I think i would also prefer the nikons 2 yr warranty and £100 to buy a tidy tripod.