ok, so here's what's up...
A) any tampering w/ your optical while it is under warranty will void your warranty, regardless of whether or not the drive has an apple stamped on it or not.
B) if you're doing that anyways, don't use overpriced Apple logo hardware. try this link
a bit of a price difference huh? don't worry too much about the uj-845-c vs. -b. a google of the "-c" version turns up acer laptops w/ it in there systems, so that means it's not Apple specific. if for some reason your iBook doesn't reconize your drive natively (the hardware might be recognized, but iLife programs wouldn't be able to burn to it), u could just install patchburn and all should be well. :-) don't worry about the bezels being different either as u would be able to simply transplant the one from your iBook onto the new one.
btw, there's also a uj-846
out and about, yet i haven't seen it in the US shops as of yet.
C) before doing this consider whether u have the money or need for further upgrades. if you're going to almost completely disassemble your computer do u want a larger faster hard drive as well? the upgrade process is doable w/ time, patience, the right tools, and the pbfixit install guides, but is much more laborious than the vast majority of PC notebook upgrades. regarding need: how often do u use your burner as is in the iBook? i have a 16x burner in my desktop so anything i may work up in iDVD i can just drop over the network and burn there. i also have found that i rarely even use the CD burner as is. if this is the case for u do u really need the dvd burner? again, if u do want/need one a larger HD would serve u well. i.e. - ripping a dvd to make a backup of = 8.5GB+ of space. if u write the copy to a 4.7GB image your @ 13GB for just one project. if u get the burner and stick w/ your HD u also may want to do a custom reinstall of OS X. u'll be able to chop the install size in half if u take s hand in what u want on your system.
hope this helps.