• First of all. A physical box is most commonly superior to a VM in terms of performance, but you may not always need that extra performance. If so, a VM may actually be a good choice. I am definitely not a virtualization fanboy, but in some cases it is actually an acceptable option in terms of performance, and definitely the cheepest.

    Regarding instances, there is nothing wrong with multiple instance on a single server, and as far as I understnad it, SQL Server 2008 gives you downgrade rights so that you don't have to buy extra licenses to run both SQL Server 2005 and 2008 on the same server: http://download.microsoft.com/download/1/e/6/1e68f92c-f334-4517-b610-e4dee946ef91/2008%20sql%20licensing%20overview%20final.docx

    I would however, as said, strongly recommend that you don't mix different environments (production/dev/test etc) on the same VM, as malfunctioning patches then will bring down multiple environments. You should be able to test all patches in your test environment before releasing them in production.



    Ole Kristian Velstadbråten Bangås - Virinco - Facebook - Twitter

    Concatenating Row Values in Transact-SQL[/url]