Like most schools, we shop around. But we, like others, use CP Ltd. Joe is fantastic, and beats quotes of all competitors.
We've just bought 100 new PC's, and as a gesture has upgraded the RAM for us on all of them.
I think for me, a smaller company is better to use as they offer that 'personal' approach. I know if one of PC's is faulty Joe will do is utmost to fix the issue.