I agree with he guy above - if you head to KL Central on the KLIA Express form the airport (if your coming that way) then get on the overground train to Pasar Seni, youll be right in chinatown. If you find the reggae bar (look out for the guys flyering for it - and say hi to everyone for me if you pop in
there are two back packers places right there, one of them i stay in if i miss the last train home as its cheaper than a taxi, ive got a bed in a dorm there for RM10 before!!
theres lots of very very cheap places in KL to stay. if you stay in chinatown, its very easy to get around KL from there. theres lots of stuff to do in KL! if you want any ideas drop me a line. im english but my father lives in taman tun (outside of KL) and i live there every summer so have spent a lot of time dong the tourist spots but finding the cheap local ways around
one bit of advice, if it starts to rain dont think youll get a cab, malay cab drivers mostly stop for the rain
but have fun!! ill be out in KL again in a fw months :D