Yes, that is correct -- a hold is placed on the funds initially.  Many countries impose limits on how long funds can be held, so if your delivery date is some time away, the hold can disappear.  Dell does not charge the credit card until the system ships (and bear in mind notebooks are almost entirely built in China, so that may happen some time before you see a valid tracking number, which you won't until the system arrives in your country).  
I bought a laptop and docking station and Dell immediately billed my credit card. The charge was pending for a few days then seemed to go away. Is this done so they can make sure the credit card payment will work but not actually charge you until the items are shipped?
Why did Dell bill credit card, then remove charges?