I need a new bookkeeping system

After spending several frustrating and confusing hours organizing a year's worth of invoices, I realized I need a new system. The paperwork had piled up because of the massive time suck called grad-school, but that's not the biggest reason I need a new system. Going through all the sales for the last tax year (July 2009 - June 2010), I see that I'm not getting the information I need from my records. I created my system to track one book, Traveling Blind: Life Lessons from Unlikely Teachers, a...