MySQL or XML for Flash shop?

Hi there, I am working on building a very simple online shop that also has a database of the orders that have been made. I have been doing a bit of work with XML and wondered if this would suffice to use as the database for a shop, the database only needs to have text details of orders, it will not hold details of products as there is only one product the shop will sell.

It seems that MySQL is normally used for this kind of thing but I am only trying to create a very simple database and as I am reasonably happy with XML in Flash wondered if this would suffice. This would mean I could easily build a user interface in Flash for the shop-owner to access the information (it also saves me having to learn MySQL).

The shop would link into a Paypal shopping cart which I will probably buy rather than make myself.

I am also wondering about the security side of things, obviously payments will be processed within the Paypal website but how secure would the database be, are there any precautions I should take? What sort of hosting services should I be looking for?

Your help with any of my questions would be very much appreciated.

Thanks everyone,

Hectors