Man, if you're playing a Centaur truenamer, between 4 RHD, a +2 LA and a -2 to Intelligence, I'll GIVE you those +10 for free (assuming you promise to stick to truenamer and not go into, say, wizard wonderland) and you're STILL going to suck more than a black hole.
Driders are iffy for horseshoes, UMD or not, merely because I don't think you can actually shod a spider's feet (and if you did, you'd run into the other problem of having the shoes nailed on).