As I already mentioned a few days ago, previewing gamer pictures and themes on the Xbox Live Marketplace isn't exactly a shining example of user friendly interfaces. Part of that problem is that there is no easy way to look at the plethora of Marketplace content on your computer when you are away from the console.
It's not that people aren't trying to fix this in different ways. For a while there was a site called Dashboard Themes which let you preview and comment on the various dashboard themes in the Marketplace. Unfortunately, it has since gone under due to a lack of resources. Individual content suppliers like Disruptive Publishers maintain their own preview sites, but they don't cover all the content. Microsoft also has a Marketplace section of Xbox.com, but that site isn't the easiest to navigate, and it also doesn't always include all the latest content that is available on the console.
What Microsoft really needs to do is launch a complete interface to the Marketplace which can be accessed through a browser on a computer.
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