I've been using Quickbooks pro since 1997. My first copy came with a computer I bought from an old trophy company that sold me Casmate Pro as well. Later I bought QBP2002 which I used for 3 or 4 years. Now I've been using QBP2006. I have 2007, but I haven't bothered using it.
In the early days, I just used it to create good looking estimates & invoices, as well as for writing checks, but I did my bookkeeping by hand still. Later I got some more training & switched over to running the QBP as my complete set of books.
It was a chore to make the transition, but it has been a vast improvement.
I do not use QB to track my inventory however. There are too many componants that go into my signs & I don't write up jobs with a reference to feet of materials, so it would be a lot of work to try to debit a running total of all my inventory for every sign that goes out the door.
What I have started doing, is a quarterly journel entry that assigns one approximate debit of the usage for the quarter. that way, when my sign supply (COGS) purchases are made, my "inventory" goes up, but to offset it, maintaining a semi accurate running total, I have to record these debits to that running total. In this way, I can claim the deduction from my gross sales for all the inventory used, but not for the inventory that will carry over to next year.
This is also good for a record against any insurance claim if, god forbid, anything ever happened to cause the need for that.