I use
Diabetes Pilot on my Pocket PC phone and desktop. Since I always have my phone with me I find this works much better then a notebook, one less thing to carry. Also, the fact you can get some analysis of the data instantly on the phone (daily average, 7 day average, glucose graph, estimated h1AC, etc) makes controlling my blood sugar a bit easier.
Finally I'm a gadget freek I find it actually helps me want to control my blood sugar as it makes it a bit of game trying to drive down my various averages.