I now mine Litecoin.
If you read up on Litecoin, you will realize using scrypt is much smarter...something BTC should have done.
It should be valued around 25% of BTC, so is undervalued atm. There will be 4x more LTC produced than BTC...and LTC is harder to get (cost wise). As a couple 7970s...
What is funny, is I never in my wildest dreams imagined Bitcoin would take off like it did.
I had over 250 of them. Gradually trading them all for silver or XBox modding tools. I have a pound of silver coins and two modded XBoxes to show for what would be work about $33500 today...
The noticeable jump is not THAT great...were you two looking at benches or actual performance? I have a 9550 and will upgrade to a Phenom II shortly, but that is because I like newer items. If the 9550 is working for what you need...stay with it. While the Phenom II does increase performance...