Saving hard drive info


I have a combo drive iBook and an iMac DVSE 400Mhz. My iMac has about 30 gigs free on its 40 gig drive.

I am getting ready to do a clean install and partition my iBook. Would it make sense to transfer my entire hard drive from iBook onto my iMac using Firewire target disk mode?

Is it as simple as dragging my hard disk icon onto the other machine and it will transfer the entire contents onto my iMac?

Will having OSX stuff and another system folder on my iMac hurt my iMac?

I have been backing things up onto CD's but this seemed like a safer, more comprehensive way of it works.