Tracking campaigns - This is Really Screwing Me Up

Hey Guys,
Quick question to all of you t 202 experts out there. Is there a way to track conversions in ppc when a visitor is sent to a page, and then needs to click on another page (sales page), and record if any sales were made from the initial keyword. Let me provide a crude example below:

Someone searches specific product on google, lets say "South Beach Diet"
>>>>
my ad shows up and it says something like this

South Beach Diet?
Looking to try the south
beach diet. Better read
this!
www.xyz.com/southbeach

they go to my lander, which talks about the dangers of the south beach diet, why it doesnt work, yada yada yada...

At the bottom of my article i have a link to "The top 3 diet products"

The user clicks on this link, and they are directed to a page where i have a side by side comparison of the "top 3 diet pills" or whatever.

>>>>

Then the user clicks through one of my affiliate links (say, some **** berry pill or something), and makes a purchase.

My question is, is there a way for 202, or any other tracking system for that matter, to record the keyword that resulted in the sale, in this case "South beach diet"

Short Example: Ad (goes to) landing page (goes to) another page on site (goes to 3 different affiliate products)

Is there any way to track this? Let me know if your'e confused. Thanks.