Megane computer

Hello everyone:

a query I am about to buy a renault megane model 99 or 2000 someone knows if the topic of the on -board computer is a topic that brings complications and in the supposed case that must be changed it is very expensive or can do it yourself? That is to say buy the computer and change it? I ask them why it is the place indicated to do so since some acquaintances of mine have scared me a little with this topic and in passing. And how many I will do well because I look for it apart to interfere with already very much thank you all and greetings.
Uurguayan