Amarok seems to be a very good music player, especially with large music collections.
VLC is very good. Xine is also good, though it's really a backend for other programmes to use.
Pidgin is a good chat programme. It's available for Windows as well as Linux, and seems to handle most chat systems very well.
Linux actually handles nearly any device without the need to download any drivers. GPUs are the main exception, due to the way Nvidia and ATI have in the past kept their drivers closed-source. The Nvidia drivers seem to be pretty easy to set up as long as you check the documentation first. I have never had any problems, though some people have had a bit of bother. Just check the Nvidia forums here. There is normally someone around that can help out if you do get into difficulties.
Anway, Welcome to the wonderful world of Linux. Have fun, and don't be afraid to ask