Hi there!
Im running a little Office with some employees. Since its a little Office, all power costs are included anyway.
Lately i thought to do some bc mining while the computers are not in use (~15hrs a day).

Configuration(s):
6x i5-3570K @3,40Ghz + Radeon HD 7950
1x i7-2700K @3,50Ghz + Radeon HD 7970 (my boss computer )

What i've read so far: If i would do "single mining" with each, it could take several months to unlock any 25btc key.
So i thought about doing pool mining with all the computers.

I compare some data from https://en.bitcoin.it/wiki/Mining_hardware_comparison to get the total mh/s:
6x HD7950 = 6x500MH/s = 3000MH/s
1x HD7970 = 650MH/S

Means a total of 3650MH/s with all my office computers.

Now my question: I did read that pools usually pay you for your "work", means by your MH/s, correct?
So would it be worth to add each computer to a pool?

Which pool would you suggest? How much would i get in average by running each machine for 15 hours a day?

Im new to bitcoin, its somehow complicated since its "very different" to anything i've seen so far.
But i want to get into the boat

Please help me and give me some hints, i fear im absolutely lost without...