B&W Speaker Placement


I am very new to the "high end" audio game, and would welcome any suggestions on speaker placement for my system. First, my room is 15 X 19. With the listening position 13Ft. from the speakers/TV. My system is as follows.
Lexicon MC1 Processor
Marantz MA500 Amps (5)
B&W CDM7nt (front)
B&W CDMSnt (rears)
B&W CDCCse (center)
Pioneer Elite DV-37/DVD&CD
Musical Design/Aura Speaker wire (are these decent?)
This system is very clear & detailed on movies, however on music, I dont seem to get the WIDE or DEEP soundstage that I want. Any suggestions for a rookie would be welcome.
fleetwood
Hey, Thanks again. Looks like I need to experiment ALOT with placement to find the correct position. Great info @ Audioasylum as well.
I've done a lot of experimenting with speaker placement and find that I get the best results spreading the speakers apart as much as possible while keeping them away from room surfaces such as side and rear walls. Also I have found that the sound stage collapses with even a slight toe-in so I have the speakers facing straight out with no toe-in at all. My room is 13 x 21 and I have the speakers on the short wall a little over 5 feet from the rear wall and roughly 2.5 feet from the side walls.
My speakers sound best about 1/3 into the room with a listening position about 1/3 from the back wall.