But the vast majority of US software patents are not patentable in Europe. If the US patent system would impede progress the effect should be a stronger European IT industry. I am doubtful of that though.
One still stay away from stuff that is patented in the US as a European company though, most European companies want to go to market in the US sooner or later.
That's actually a pretty great argument that software patents are a good idea for the US, it prevents foreign copycat competition from soaking up the market on us.