Am I doing something wrong?
You're doing three things wrong.
1. You're mining BTC with a GPU and expecting some payouts
2. You're mining at Slush's
3. You're not posting in Slush's pool thread.
![Tongue](https://bitcointalk.org/Smileys/default/tongue.gif)
With a 7950 you should be mining at some of the scrypt pools that do auto conversion to BTC, like Wafflepool, and Scryptguid. Mining BTC directly at 500kH is just turning electricity in to heat and noise for no other gain.