i do use the vbulletin support, it just didnt come up with the goods. Anyway...

ok in the end, my host put the vbulletin in a sub folder. and then i installed it there.

then they used the iis to say that the site is held in the subfolder and not the root.

works great.

ive posted this solution in the vbulletin forum to help other windows users who want it in the 'root'