The original X disks are gray - Jaguar disks are white with the "X" in jaguar pattern.
If you're not in a hurry Jennie, I'd just wait for Panther. Otherwise, I'd have a good look at eBay or OWC. The hour or two needed to do the upgrades is worth the dollars saved, IMHO. After all, if my experience is anything to go on, you won't have to do it again.
None of my OS X installs have needed reinstalling, ever. I've changed my mind on partitioning and added hard drives - but the installs themselves have never let me down. Not sure what the deal will be if you buy a retail version of Jag now - when the cutoff will be for free/almost free upgrades to Panther. This isn't a tidbit that Apple has given us yet, and until we have a firm release date for Panther, it will be speculation at best.