Cgminer says my 7970 is hashing at 540-550Mhs yet the pool reports around 440Mhs. Any ideas on where that 100Mhs might be hiding?

u run the wrong settings dude, u have to add --scrypt in your miner .bat or add this via console at start!
Like this:
cgminer.exe --scrypt -o stratum+tcp://stratum01.hashco.ws:8888