NolaPro might be free, but it's far from lightweight. It has an impressive array of accounting modules, from accounts payable and billing to time tracking, point of sale and inventory. Indeed, to my admittedly non-CPA eye, it's about as full featured as QuickBooks. And speaking of QuickBooks, you can even import your data into NolaPro, if you're coming from there. Overall, I found NolaPro far more powerful than GnuCash, another free accounting package which we looked at a few months ago.
If you want to give NolaPro a spin before you install the app on your computer, but sure to try out the NolaPro online demo, which lets you fiddle with everything using sample data.