choppy, but no lag

I just got the radeon x800 xl, I have all the latest drivers installed and evertyhing, I played doom 3, hl2, counterstrike, and all did great except the surroundings. I can't explain it, hl2 lagged a bit, but it was the demo and I heard the demo lags at all times. Doom 3 ran on High graphics no lag, but I could see like lines in the walls, I can't really explain it, some things were just choppy like i could see where the wall met, there were lines there. on counterstrike my ping is around 13, no lag, but still I can see those lines, not on the main character, but mostly on the surroundings, I was wondering how I could fix this.

P.S. very noobie question, but under display adapters I have ATI radeon x800 xl and ATI radeon x800 xl secondary, what is secondary. Thanks for any help.