The configuration your thinking of will work just fine as long as you run the reciever in 5 channel stereo.Your speakers may be rated at 100 watts, This is their maximum power. In reality you'll be using probably less than 5 watts per speaker. Also, You will not "blow" the speakers up because your reciever puts out 100 watts and your speakers are 100 as well. Its always better to have more power on hand than you will actually need. Because your speakers are all 8 ohm, you wont have any problems with impedance either.
Many 7 channel recivers are really 5.1 and zone 2 or 7.1, Which means that you can use the back 2 channels for a seperate zone, meaning you could listen to one source from your main speakers, and another source through the zone 2
