Well, I don't feel comfortable replacing the touchscreen, as when I did it on a HTC Prophet (QTek S200) both touchscreens I replaced were of poor quality. My current Defy has a misbehaving touchscreen (left 15pixels won't work, pressing 1 on the keyboard is impossible) which sometimes doesn't even record touches, and a Bayer camera which got some water in it (so much for being water proof xD). And I guess who tried to repair it forgot to re-add the three plastic rings which keep the logic board and the rear cover at a certain distance.
@measel, where did you get your touchscreen? How much time ago and is it still working? I found
this website, it claims they're original from Motorola (but I haven't found the small plastic rings anywhere - I tried with some snorkeling rings, they weren't of the right size unfrotunately).