Using a taxi is a pretty affordable affair. Only thing that you should be aware of is that when you must take a taxi from the airport to the city, be careful of the cheating taxi drivers. They easily take you around Brussels, and before you know it, you paid 50 EUR, instead of 25 EUR for your ride...
WHEN IN brussels YOU CAN ORDER TAXIS FROM THE CENTRAL DISPATCH OF THE FOLLOWING COMPANIES:
ATR: TEL. 242 22 22
AUTOLUX : TEL. 512 31 23
TAXIS ORANGE : TEL. 513 62 00
TAXIS VERTS : TEL. 511 22 44
Please check the link below in order to recognize Brussels Region taxis and avoid problems with "foreign" taxi-drivers applying most of the time their own tariff!