Regardless of choosing the right software for your needs, if you are moving from paper ledgers to a computer system, it is *vital* for you to plan how to do your system's backups. I can't over-emphasise it too much, because I have seen the stress and chaos at first hand of having to re-enter four years worth of paper, after I was called to look at a nearby neighbour's PC which had experienced a crash which turned out to be irrecoverable. His poor wife was given the job and has hardly forgiven him even now.
One of the lessons from that episode is that I would generally not recommend the use of a "general" PC that you use for surfing, mail etc as a bookkeeping system at all: it is safer to avoid all unnecessary chances of a virus or worm getting in there. A second PC for purely invoicing and running the books could be a very moderately-specified machine, and cost very little, and then it can be kept well away from public networks. The risks these days are a lot higher than they were even three years ago.
Paper books are extremely resilient and have excellent archival properties; electronic data does not. Over a seven-year period (or however long the auditing record requirement is for your tax authority) you could very feasibly change PCs, or at least change to a new hard disk drive. Historically it has often proved to be that over this time frame the backup system you had in the outset will no longer be working or supported at the end. It is always easier to cope with this if you plan it ahead.
Bear in mind also that copying stuff to CD-R is *no longer* a viable backup strategy. These things (both the disk AND the blank disks) are now so cheap that there is really no profit to be made on them, and therefore no longer any incentive for the manufacturers to produce ones that work dependably. There are so many counterfeit blank disks on the market and they *often* just lose data completely after only a couple of years. My opinion is that this is also the reason that my very very old 12X QUE!Fire external drive still seems to read just about anything I put in it, while the far newer drive in my laptop experiences read errors on anything that is not a perfect copy. Even though it probably a sign of my impending old-fartdom, I would still keep some sort of external tape backup unit going, if you are going to be putting business-critical data like your books on there, and from time to time make a c:\trial directory and try doing a small restore test, just to keep an eye on the safety of the data.
As for software I personally like GnuCash which is free and which runs on Linux or Unix, but it sounds to me as though you'd prefer a Windows package.
