ISO200 is the lowest you really need...
www.dpreview.com has tested many nikons with iso200 being the lowerst point in direct sunlight and the results are no different from using iso100 on canon's... when you have a higher ISO you can use shutter and aperture to get the best photo...the trade off is grain ...but iso100-200 you wont notice the grain at all on a SLR
NIkon's get more grain than Canon's but NIkon cameras produce sharper and Crispier images than the Canons...
Ever since I have switched to the D70 and I have never missed the lower ISO feature that I used in the past.