Weldiger, I'm a little muddled - are you wanting to install the Zip drive in something other than the igloo iMac or the iBook? (Because you can't install it in either of those machines!)
Parker's suggestion that you get an external case - USB or FW - is probably the way to go, if you're convinced you need one. Gives you flexibility to use it with any machine.
However, what kind of connection does it have? If it's a SCSI connection, you're probably out of luck. If it's an IDE/ATA connection you should be fine.
And even though the Zip drive may be cheap, it's media is nowhere near as cheap or ubiquitous as CDRs or DVRs and nor is it as reliable. Plus a Zip disk holds a whole lot less.
Me...I'd forget the Zip drive. I think in a few years it may be akin to owning an 8-track tape deck.