Let me guess .... You tried to install something like Yahoo mesenger or WindowsLive messenger?
Ah .. these are "Win only" program (exe installer). Wont work!
But .. you can use BOTH in Kopete (and more if you like to) at the same time.
Kopete comes closest I think for at least you will have your webcam, something popular (?) Pidgin still mis.
For WLM you can also use aMSN
In fact there are more clients Like Gyachi etc... But, well believe me, Kopete is easy and works (at the moment that is, LOL).