Google has aggressively gone after Amazon affiliate sites. If it uses the XML feed, it gets heavily penalized or banned (yes, banned) pretty quickly due to the duplicate content. Scrambling or spinning the content doesn't work. An A-Store can work if you add your own unique content to each page; otherwise, you do not have any content on the page due to the iframe.
Passing the links through a script that is blocked in the robots.txt file, as Matt Cutts recommended, does not work. Google will still penalize the site, even if it has 100% unique hand-written content.
I tried several scripts over the years. The best one that I found was a freebie that several of us heavily modified. That was the Freekrai.net script. I don't think it is available any more, but it was the easiest to modify if you are a PHP developer. The nicest part is that it didn't need a database. All product data was real time. We evaded Google's penalties for quite a while by scrambling the content, but when Panda came along all the various sites that the group put together were wacked hard. None of them survived, even though each used a different method to cover the Amazon affiliate tracks.
Just my 2 cents worth regarding Amazon scripts. You have been warned.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin