Need help!! Just got new house and am not sure how to adjust old speaker config.

Just got new house, and HT room is rectangular. The old owner put the tv on the two walls closest to each other, whereas I am moving the tv so that it is in the long end of the room and configuring the room as such. The old owner's system consisted of two in wall speakers at opposite ends of the couch opposite the TV(I assume they were the back surrounds) and two ceiling speakers (they were within two feet of the in wall speakers) Will my theater sound right (I am not an audiophile, just want it to sound decent) if I hook the ceiling speakers up as the Front speakers, and the wall speakers up as the back surrounds? I don't know how to make this work otherwise and I do not have a center speaker. If anyone has any suggestions as to a better configuration using these speaker types, I would appreciate your help... I am completely clueless about this stuff.