Mikvitu, I've had DIII centers with speeds ranging from 40 to just over 60 and I don't even run a fast break. My current team has two centers with 40+ speed and two under 20 speed (one under 10 speed). I have a PF with 60+ speed who hasn't maxed out yet in speed.
I like faster players in general, especially for running the press. But it really depends.
Whitey, I'd say it depends what O/D you run and what kind of offense you like to run too. I like to go uptempo and my team averages between 85-100 points per game almost every season, so I like fast scorers on my teams (SF David Crampton 40 ATH/67 SPD/64 LP/90 PER/60 BH and C Christopher MacMahan 51 ATH/42 SPD/84 LP and PF Paul Griffin 48 ATH/63 SPD/49 LP/33 BH). I also like to disrupt my opponent with my press, so I like having athletic/fast defenders, even among my big men (like Jerry Johnson on my DePauw team with 62 ATH/43 SPD/60 DEF at center).