Speaker placement suggestions?

Hi everybody. I just bought a pair of B&W 805's on Friday and wonder if anyone has any suggestions regarding their placement in a 12 X 20 room. This is for 50% home theater & 50% music. I use a REL Strata II for the low end and a 40" t.v. sits in between the mains.The matching stands are on a wood floor, the room has a heavy 8X10 rug. Any suggestions on what crossover frequency is best? I am having trouble choosing between 49hz and 59hz. 49Hz seems a bit empty, and 59 seems a bit boomy. Is get Radio Shacks sound level meter worth using? Thanks to all.
I also have a pair of 805's in my 17'x 14' room. What you need to focus on is having the speakers and the listening position form an equalateral triangle. My speakers are 7' apart and 7' from my listening position. Placement from rear wall to front of baffles is 48" and 45" from side walls to center of tweeter. Yes getting a Radio Shack DBL meter is a must. Make sure you get an analog unit. This setup, for me, is strictly for 2-channel sound reproduction and works very well.
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