I would say most small businesses I know actually don't use any specific financial software, but do everything in a spreadsheet package. Excel rules the small-business world in a lot more ways than you might expect. You can probably do most similar things in LibreOffice. Now whether this is a good idea varies. The con is that you can end up with a sprawling spreadsheet-and-macros mess, but the pro is some flexibility in doing complex things, and simplicity in doing easy things.

GnuCash is not a bad option either, but it works best if your processes map on cleanly to one of its default processes. It does standard double-entry bookkeeping just fine. Its documentation is pretty good, also. But if you want to be doing significant scripting or customized report-generation, I find spreadsheets easier than dealing with GnuCash scripting+reports.

Depends on what kind of business to some extent. For example, if you need to interface with shopping-cart software or something of that sort, you may have more specific requirements.

This is excellent advice, and I would add a bit more to it. Are you looking at Open Source because you're a Linux guru who is used to managing such types of systems, or because you want to save the money that you'd otherwise spend on QuickBooks and Windows licenses? If it's the first, then also consider how much time you'll have to be the sysadmin on top of your other non-IT duties there. If it's the second, then forget OSS. You'll save less than a thousand dollars, in exchange for which you'll have another learning curve thrown at you while trying to open your first restaurant. Restaurants have, as I recall, an 80-90% failure rate in the first year; don't give yourself more to have to deal with to save a tiny bit of money. Your IT infrastructure won't be large, but it MUST be functional and reliable.

However, on business financials....do NOT skimp on this. You need to track costs, billing, etc.....this is especially true at EOY when having to deal with your CPA, and the IRS. It is tough enough to have to deal with the myriad of laws and regulations the state and feds put on small businesses, go with something that is set up to help you out and accurately track finances, payroll, etc.

I'd recommend going with Quickbooks. It is almost a 'standard'...which makes it easily portable between you and your CPA.

Don't cheap out....get a good CPA to help keep you honest on your taxes....a good one will help you squeeze out every penny to keep for yourself legally, while being conservative enough to keep you off the IRS' radar.

This is business...and $200-$300 invested on this....will help you out in the long run...and hey, you can write the QB purchase off on your taxes.

Nowhere did they say they wanted to "cheap out" or "skimp out". They didn't say they weren't willing to pay money. They said they wanted to support the OSS community.
If you honestly thing that Quickbooks is going to do a better job at handling the requirements for any small business than any OSS accounting software plus $300 of customization would do - that's fine. I'm sure there's plenty of people who would agree with you. But don't pretend this is about money.

I may be biased, but I have to agree.

I work for a FOSS based software company; we charge for installation, support, training and custom development of a GPL licensed ERP solution.

Our clients get a much cheaper solution and we contribute back to the platform (bug fixes, new FOSS modules, etc).

I won't plug my company, and the restaurant is probably not based on our country anyway, but I'd consider this approach.

Have you ever really put this theory to the test? I called around my city and was able to compile a decent list of accountants who were familiar with and openly supported PostBooks [xtuple.com]. PostBooks is cross platform and is released under an OSI approved license.

Of course finding that kind of thing out would require a good 20 minutes of a busy professional's precious time so I'm sure you'd be much better off just going ahead and buying Quickbooks without a second thought based on advice from a web forum rather than actual interactions with real accountants.

You would think that a company like Genentech with 11,000 employees would know a thing or two about whether or not their Google Apps [techrepublic.com] email solution meets all of the regulatory requirements they are subject to.

You seem to be confusing the free version of Google mail with the paid Google Apps for Business which defaults to not serving ads. [google.com]

Zimbra has Outlook and mobile device integration, all secured by TLS/SSL

I don't even know what that means in the context of an email server? Are you talking about a persistant connection between Outlook and the email backend or a VPN?

In any case, Zimbra can do more than deliver Facebook status messages, they have a pretty broad customer list [zimbra.com]

Zimbra has had remote wipe [zimbra.com] for years. Even Google Apps has remote wipe [google.com] capability. And they can also enforce encryption and other ActiveSync security policies.

Maybe Google doesn't know anything about the government sector. [google.com]

Believe it or not, there is competition in the email server market, but most companies don't bother because once they buy the CALs and build a server infrastructure to run their other Microsoft applications, Exchange doesn't add much more to their Microsoft cost. But some companies are still finding it cost effective.