Tax on order from USA

You'll pay something like a €10 customs handling fee, plus 21% VAT on what the (ex VAT) list price of the product is in Belgium.

VAT is paid upon the declared value of the item.
Not on the Belgian equivalent, most items I have imported have no local or European equivalent.
All of this information and the relevant costs should be available from the importing company.
Customs officials will only open a package is they are suspicious after scanning or following intelligence.
This has never happened to my multiple items over several years.
All comments based upon personal experience, others may have differing experiences.

I second what Mark is saying. From personal experience twice, they tax you 21% on the declared value of the laptop mentioned on the customs declaration form, filled by the sender. They don't have time to open each and every package as asses. One thing to note is that if they send by USPS then it may be stuck at customs for a longer time than if its by Fedex/UPS where you can expect it faster.

Apart from VAT and handling fee, there is also a duty % applicable depending on the item and its value. Is there no duty applicable on electronics / laptop ? I guess there is a duty applicable on most products if the product value is greater than 150 Euro. Below 150 Euro, probably you only pay VAT.

***Typo***

I second what Mark is saying. From personal experience twice, they tax you 21% on the declared value of the laptop mentioned on the customs declaration form, filled by the sender. THEY DON'T HAVE TIME TO OPEN EACH AND EVERY PACKAGE AND ASSESS. One thing to note is that if they send by USPS then it may be stuck at customs for a longer time than if its by Fedex/UPS where you can expect it faster.