I think that's a good question and I'd like to hear results from other vendors, too.

I currently have 2 products, one is shareware and the other is a premium option for a freeware product. I have a high conversion for the shareware, but it doesn't get a lot of hits. Since Jan 01, closure rate for the shareware is 62%; for the freeware it is 23%.

One thing I noticed on your page is that you're offering a $12 CD for a $5 product. Unless you have a high percentage of people opting for that, I would seriously consider removing that option. I'm probably not one to be offering marketing advice though, but sometimes it's easier for someone else to see things.

One extra technical step you can make is start tracking the performance of your sales pages with Google Analytics to establish if one part of the sales process is causing people to drop out more than others. Also by tracking the page in Google analytics you can run different templates at different times and measure the conversion rate on each. http://home.plimus.com/ecommerce/tutorials/google-analytics-tracking
 
I think the page is fine -- the box shot really adds. Maybe it would be good to show a video type graphic in there as well perhaps with a human face. I would also put a heading above the testimonials and run them with quotation marks and attribute them to name plus surname initial. Given the low price it does seem great value for money. Maybe also try bringing the Rateit 5 starts element to the top of the page alongside the product logo. Also it looks the sort of product that other sellers should be interested in selling as affiliates. Might also make sense to offer a subscription version. Derek, Plimus