My upfront disclaimer is that I do not use the software I am mentioning, I just manage the "server" it is running on and make sure everyone can access it, etc...
That said, Quickbooks in Multi-user Mode has been very easy to implement and maintain. It runs just fine on a win. 7 machine (with a good backup scheme). The cost is basically an additional user lic.
Our setup is within a Win Server 2008 R2 environment, so the remote connection part is very easy, so that may be a sticking point in your case.
Looked into doing the cloud route with Quickbooks, but for our situation where there are only 4 people connecting to the central "server", the cloud solution cost was much more expensive.