how do you do *proper* ad-tracking? (conversion + EPC)

hey there,

I would really appreciate some advice on how to do proper tracking and testing:

I'm running image-ads on the google content network and would like to test which ones ultimately make the most sales (not just highest conversion, boy, oh, boy did those 'free beer' ads convert well, but nobody bought the brazilian hot-wax product. ok, ok, kidding aside...)

- do you use Google itself to split-test the performance of the individual image-ads and keywords (i.e. pure conversion tracking)
- then, once someone clicks through and they land on my landing page, what do you use to track which landing page converts best (highest signup rate)
- when they eventually buy a product (CPA or clickbank or even my own), how do you then track back from there and figure out which original image ad (combined with which keyword) and which landing-page combination resulted in that sale, so I can figure out what my EPC are and optimize those combinations even more.

I know you get some stats from Google Adwords itself (conversion rates for images/keywords), I guess I could use website optimizer to check different landing page performances, but then .... tracking202 ....? any other tool?

is there a tool that does it all in one go?

many thanks in advance

Veit