If you haven't heard of the CeBit Trade Show on CNN or anything, this is what it is...
The CeBit is an expo for high tech things such as mobile phones, PCs, games, etc. It is held every year in Hannover, Germany in about March and is attended by important people such as Bill Gates and other CEOs of tech companies.
The CeBit is an advantage for the Xbox. Since the CeBit is held this week, it will strengthen the Xbox's launch (14. March) which is at the same time as the CeBit. The CeBit can give thousands of people attending it a good idea about the Xbox and its games, so more people will buy it. The CeBit isn't really like the E3, ECTS, or the Tokyo Game Show however many game producers will be attending it.
Let's hope the launch of the Xbox in Europe will be a good one and better than the Gamecube's.
(For your information, the CeBit doesn't only have Xbox games, but also GCN, PS2, and PC games.)