Thanks for the support, guys. I invested a lot in this build - money and energy - so it was not without sadness that I decided to abort it.
The most frustrating thing is that it worked fine with VGA, no random clicking and some 5-10% jitter (pretty tolerable)... it was only when I switched to DVI that the problems really started.
Considering what Wood said, actually there are too many variables here, the laptop is new, I have a 21" monitor, I bought a wireless keyboard, everything quite near the cintiq....
Right now I'm using the Intuos3 XL tablet that I bought on ebay - it's still working, even after the fireworks that happened (i.e. that I caused) on my other build... that I also aborted.
If I decide to do another build it will be a retry of this one, I had great plans for it!!