Crossover Office Pro to run your QuickBooks (or, WINE) and yes you can print. I do
Debian GNU/Linux (don't trust your business to Microsoft or some fly-by-night Linux distro -do what YOU want)
There are a lot
more out there. Barcode stuff, POS stuff, time management, HR amnagement -- it's all out there for you, and of course, security stuff. The biggest single advantage of using open source software is that you (business owner) are not locked into a single vendor. You are at nobody's whim to update hardware or software or pay licensing. That's some sh&^ right there, bub. Maybe someone would argue this, but I don't see how.
Everything that I listed is free except for Crossover Office. However, WINE is free and it's what Crossover Office (CO) is built from. CO adds code for certain applications to run smoother, that's all.
I didn't mention virtualization, and I won't -- small businesses don't need the headache unless they run virtualization from one machine. Qemu and Parallels are excellent. A ton of hardware has been coming out to support virtualization....keep your eyes peeled if this is what you need.
I find that I can set up a butt-load of business apps for a small business right on their Intranet. Collaboration is not an issue at all, unless it's in your best interest to say it is. But you'd be lying. ;) It's very cool, way cheap, very robust and how many times can I write reliable without getting a cramp?
My customers like paying me a hell of a lot more than paying Adobe, Intuit, Microsoft, Siemans, et al. I'm a lot cheaper, get them rolling a lot quicker, save them beaucoup bucks, and they like that money they give me feeds my family and not some propoganda or lobby machine. They think it's cool that I can manage their (whatever) from the ass-groove in my sofa, too.