What kind of bicycle do I need?

15 years is a very long time in bike terms - there have been huge advances over those years. I'm not into mountain bikes at all (have owned a couple) as they are so slow compared to road bikes... and if you are anything like me (and this being a Ferrari board) speed is that key - riding fast is much more fun than riding slowly and if it is more fun you'll do it more often! I recently bought a second hand all carbon bike to replace my 5yr old commuter - the difference is night and day