no9t9 - 4:36 pm on Jan 21, 2005 (gmt 0)

i had my ad block (120x60) on the right as you did but later moved it to the left side. My CTR has doubled and has NEVER dropped back to previous levels.

I think the left is better because most people naturally read left to right and also the left side is always visible without scrolling. Sometimes on the right, it is outside the window view and never gets seen.