There are several factors that one needs to consider when deciding between Microsoft SQL server 2005 Standard Version and Microsoft SQL Server 2005 Workgroup edition. There is a vast pricing difference, per processor, $220.00 per month for the Standard version and $55.00 per month for the Workgroup version, so I will be examining the major differences between to the two.
The first major difference between SQL 2005 Workgroup and sQL 2005 Standard is the number of processors that are supported. With the Workgroup version, there is a maximum of two processors supported. With the standard version the only limit is the number of processors that the Operating System supports.Two processors may seem like plenty, but there are a lot of enterprise level applications out there with absoultely massive SQL databases and require massive horsepower to access the database efficiently. Another difference between the two SQL versions in regards to processors is that SQL Server 2005 Standard natively supports 64 bit processing whereas SQL Server 2005 Workgroup does not.
The second major difference that I wanted to mention, and this is a big one, is the amount of RAM that the two different versions can address. I mentioned that Microsoft SQL Server Workgroup can utilize two processors, that said, it can only address a maximum of 3GB of RAM, dual quad core processors will only get you so far when There is three or less gigabytes of RAM supporting it. Depending on your planned use of Microsoft SQL Server 2005, you may need the Standard version which can address as much RAM as your OS/motherboard can support.
The third major difference between the two versions is in the realm of mission critical SQL databases. Some applications require redundancy. If one plans on having a mirrored database solution or failover clustering, then one definitely needs SQL Server Standard. If this is in consideration definitely make sure to do some research, Microsoft has some pretty stringent guidelines in place for this kind of solution to be effectively implemented.
There other differences between the two versions. I believe that I have covered some of the major ones. For a comparison chart of all of the Microsoft SQL Server 2005 versions, take a look at this link: