You know, I was sitting here thinking about this. I'm not so worried about the case strength immediately, because as you remember, I cut a hole like this in Little Stealth, and cases don't get any thinner than that one. What does worry me is I change motherboards every 3-4 months, and no two Socket A boards have the CPU socket in the same place... See the problem? I wonder if you couldn't just leave the springs on top, bring the screws up from below, and just drill 4 holes to get at the heads of the screws with a screwdriver, and tighten through the 4 small holes..
Might get you some more life outta that case if your like me.