Heya Doc, cool to see you got your new system together
I use the Catalyst 11.4 preview drivers myself and they work great for me so far. Only prob is the three blue lines bug.
About overclocking. I have done mine in the CCC (performance and then you can start overclocking there) You could also use an app called Smartdoctor if I remember correctly.
I didn´t overclock my card that much so for me CCC is fine. (915 MHZ base clock, 1425 mhz memory, 0% extra voltage, manual fan control on 35%)
Each card is different though so you should just tweak a bit and see what is stable for you.
Anyway, have fun with your new card and let me know if you get the three blue lines on the horizon thingie, I´m interested to know if all hd6970 users suffer from it.