I use logbook pro with the pocket PC add-on. For the guy above that said you have to buy a new copy if your PC craps out and you have to install it on a new one; NOT TRUE. They send you an email with your registration data in it. You can download the application from the logbook pro website and install it, it will stay in demo mode which will limit it to 50 entries until you click on help then enter registration key/unlock then you will unlock it with your key. Also you can use the backup function listed in the file menu to backup the data every few months and burn it to cd incase your PC did take a crap you would be able to import it after installing logbook pro.
I tried a few of the other electronic logbooks but logbook pro is by far the best out of the ones I tried. You can download a free demo that will limit you to 50 entries until you buy the unlock key at
http://www.logbookpro.com/ make sure to take time to learn all the features they really simplify life.