Once you've figured out your exact model visit the Sony site to see what options it had available 'from the factory'.http://img839.imageshack.us/img839/6316/ss002t.jpg
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If your model has options for a dedicated card you'll also have the option to have it upgraded with that card. It's not something you could do yourself.
So you'll be paying shipping costs, parts and labor to have it sent to the type of people who have the skill, tools and knowledge to do that type of upgrade.