DWarp9 - 9:43 pm on Sep 27, 2010 (gmt 0)
MS SQL only requires columns to be listed in the Group By clause if they're not part of an aggregate function.
So, if you don't care which value of size or price you are returned you could use:
Select category, style, Min(size), Min(price)
From table Group By category, style
Hope this helps,