I know that there is some confusion about what exactly the minimum server memory setting in sp_configure actually does. When I was at PASS I was able to ask the Microsoft guys this very question and here is what they told me.
The setting does not control how much memory SQL takes when it starts up. What it controls is a low watermark as to how much memory SQL will keep.
For example if you have 2 Gigs of memory installed, and a min memory setting on 1024 MB and a max memory setting of 1536 MB and Windows starts telling SQL that it needs more memory SQL will give the memory back until it hits the 1024 MB lower limit. Once it hits that limit it will no longer give memory back to Windows.
Denny