They are probably aiming for a simultaneous English PC and XBox release. With the delay for the German XBox version, though, it at least opens the possibility that there could be a delay with the English version if something happens to slow down development. On the other hand, they are delaying the German version until September, which is also when the English release is targeting for, so perhaps they will be able to work on some aspects of the two XBox versions in parallel, so they could be finished around the same time. Or not. It all depends on stuff we don't know, or things that have not happened yet...