Sorry, i guess my post was a little confusing and the approach of solving the issue i faced a little over simplified. The thread you point at has the latest designer with all issues resolved, thanks.
p.s. just to clear things out....
the jars i mentioned emerge from the required classes of the exceptions that occured (similarly to the other thread, sry i missed it).
So basically one would have to download the jars containing the specific classes, however the jars (more or less latest) of the related frameworks (i.e. appache logging, xerces) are found in the drools-guvnor.war.