I love
DietPower! I highly recommend it. It's easy to use; it's got an enormous database of items whose units of measure can be customized according to use; you can enter recipes and indicate numbers of servings yielded and then it calculates the nutritional aspects for you; you don't have to be online to use it; you can migrate information from one computer to another; it tracks your metabolism based on your entered nutritional input, activity output, ongoing weight, and more; you can set weight loss goals and get nifty actual vs. trend graphs; you can customize exercise entries; you can journal using it's calendars; when you want to enter a food, you can just drag and drop the item and then indicate unit of measure (ie. cups vs. ounces
the nutritional information is much more comprehensive than anything else I've seen; it has an enormous amount of information available on all vitamins, minerals, and more; you can set nutritional goals (like I reduced my sodium and sugar, and increased my protein) and then see graphs comparing actual vs. goal -- and if you're lacking something (like I struggle sometimes with potassium) if you want, it will name different foods you like (according to your entries) that are good sources.
There's more and more, but I'm not even sure you're still reading!
Just a heads-up: if you end up opting to try it out and then want to buy it, you can get some good discounts on nutrition- and fitness-related stuff like food scales, pedometers, heart rate monitors, etc. if you buy them at the time of the software purchase. I bought a food scale and a body fat scale at the same time I got the software; the prices for those items were competitive, and my software ended up costing like $30 less.....
I really do love it, and I highly recommend it. I haven't encountered anyone who's used it who hasn't really liked it and found it superior to other alternatives. It's received some awards and been reviewed positively by some fitness and software mag's, and they have a good forum for technical support and the sharing of best practices. (Like I enter all the stuff I absolutely have every day into one recipe, and then just drag and click once instead of having to enter it all every single freaking day. -- That one was a great tip!) And NO, I don't work for them or get any kickbacks, although I'm sure it sounds like I do!
I've written about it a lot here, because this topic comes up occasionally -- so do a search on it and you'll come up with more, I'm sure.
Good luck to you, whatever route you take.