Buy a laptop as tourist (without USA address)

There are a number of reasons why you might not want to do this.  First, systems purchased with a standard warranty are covered only in the US -- unless you upgrade to onsite service at extra cost, you cannot transfer the warranty internationally.  And depending on where in Europe you'll be using the system, the warranty may not be transferrable at all unless the same model system is sold there AND Dell has corporate support (in much of Eastern Europe, all sales are through dealers, which may be reluctant to support systems they did not sell).

 You cannot order a system using a non-US credit card for shipment to the US.

Assuming what you purchase meets the qualifications for international transfer of the warranty, you may be better off making a retail purchase in the US than in trying to order internationally from Dell -- the latter option will almost certainly fail.