i hate building pc's step by step. cause if you buy the mobo now, by the time you want to by the processor and ram it might be not the newest anymore. if i was going to build step by step i would buy the things that i know won't be changing too much. first would be a cd-rw, dvd, and hard drive, then the processor. you always want to know which processor you want before getting a motherboard. then you need to decide if you're going to use the integrated sound or buy a sound card. also, you can buy a case in advance cause they don't change much.