It's Official: Egypt Will Hold Parliamentary Elections in September
Obviously, these are tentative figures that will have to be revised as we see whether these groups do get organized and are able to remain united.
The Brotherhood will definitely not "take over" Egypt this year -- especially since Amr Moussa is the most likely president and the Brotherhood won't run a candidate. But it will have lots of influence and a key role in writing the new constitution.
Presumably, the Brotherhood will make deals to get religious and social clauses it wants in exchange for compromises on things it doesn't care about very much. Egypt, then, will take a big step closer to Islamism and an even bigger step toward being hostile to the United States and Israel, while moving into a virtual alliance with Hamas.