hi yall, im new to mountain biking and just picked up a 2003 hardrock. want to upgrade some components but a real newbie to the world of bike mechanics. i want to upgrade the front and rear acera derailleurs to deore or lx and possibly the shifters as well. my question is how does the difference in the 8/9 speed compatiablity work out? do i need to replace the whole drive train to deore or lx? will the 9 speed shifters along with the matching derailleurs work on my current 8 speed cassette /crank set up? any help is appreciated.

Your cassette, shifters and chain have to match.