Hi, i picked up a HP compaq D530 SFF and am wanting to install leopard on it. Trouble is - I'm a complete noob :p

I've read this: 10.5.4 installed on HP D530 SFF - InsanelyMac Forum and also seen a video on youtube of the same machine running leopard so it should work, but when i put the JaS.OSx86.10.5.4 DVD in and try to boot via BIOS, it says Non-System disk or disk error, ive also used Carbon Copy Cloner to copy the iso over to a USB flash drive, but it dosent want to boot from that either..

the only tutorials i've read on installing leopard on this machine are straightforward, put the disc in and boot, but as it's not working i'm hoping someone here can help me out - do i need to use iboot or update the bios or what?? :s