To start off there will be some limitations. Windows Vista has a 10 connection limit. So if you have more than 10 people connecting to it at a time some people will get access denied errors. Some programs keep connections open as well as users accessing other documents on this Server will eat up the concurrent connections pretty quickly. There is a TCP/IP patch out there for Vista to help alleviate some of the problems, but will still force the 10 connection limit. Only way around this is to share the file on a Server Operating System (Server 2003, 2008).
On the Vista Server create a folder in which you will share the quickbooks data file. Right click it and go to Sharing. Give all the users full control read/write access.
Since this is a workgroup environment (not Domain) you really can not push the share to all of the workstations automatically you will have to either create a log in script and put it in the Startup folder of each workstation or go to each workstation and create a mapped drive. Login script. Open Notepad type the following: net use x: \\servername\sharename (substitute x with a drive letter you want. Make sure it doesn't conflict with any drive letters on any of the other machines Q should be safe. Substitue Servername with the computer name of the Vista Server and ShareName with the name of the folder you shared) Once this is typed, go to File --> Save As In the dialog box change the file type from .txt to All Files. Name it Login.bat. Save. Take this file and put it in the Startup Folder of all the workstations. When they start windows it will map the Q drive to the share folder on the Vista server. Note: As soon as it maps the drive it will use one of the 10 connections to vista.
Install Quickbooks. Quickbooks Pro 2006 and up you can install the Database server on the computer hosting Quickbooks data files. During the Installation of Quickbooks it will ask you if the computer is going to have the data fies on it or on another computer. If you plan to use Quickbooks on the Vista Server you will need to install both Quickooks and the Database server. If you will be just sharing the datafile on the computer then just install the Database server. Once the database server is installed, move the Quickbooks data file to the share folder you created. Launch the Quickbooks Database program. On the first tab you should be able to tell it to look for Quickbooks data files in a particular folder. Choose the folder you shared then hit scan. It will find the database file. Just Hit OK and close it out.
On all of the other workstations install Quickbooks with the option This computer will run Quickbooks, but the data files are stored on another computer. Once installed choose open existing company file. Point it to the Q drive.
The database server will keep take care of the rest.
Side notes: Make sure all of the workstations are not trying to Host Multi User Access for the Database file. Only the Vista server should be doing this. To check, in Quickbooks go to File -> Utilites. Make sure it says HOST Multi User Access (this means it is turned off) If it were on it would be Quit hosting multi user access).
User licensing for Quickbooks. Pro you should be able to go up to 5 users. After that I believe you have to purchase Quantum or Accounting edition. Only the number of licenses you have will be able to access Quickbooks at the same time. You will be able to create as many usernames in Quickbooks as you like, but only the number of licenses you have will be able to access Quickbooks at the same time.