Slasher,
Whatever you do, don't buy a CD-R/RW without buffer underrun technology. I got suckered by a cheap price into buying an obsolete Ricoh burner in Sim Lim [Singapore] about a year ago without buffer underrun. After a lot of frisbees and coasters [about every third burn, and I never got a good burn onto RW media] I finally did some research.
Do some
here before you buy.
I eventually threw out the Ricoh and bought a LiteOn 24102B [internal] for about $A150 [from Strathfield Car Radio in Sydney, should you happen to be in the area] which does have the technology and have not made a dud copy yet. It is just fantastic and streets ahead of the Ricoh. Probably not Ricoh's fault, just technology marching onwards. A 2Mb buffer is all you need.
Installing a CD-RW internally into a PC is quite easy, except for one plug which can go either way. One way is right, the other wrong. Damned if I know why industrial design after all these years still gets that wrong, but aircraft still do also, as we know.
Unless you have a laptop which might require you to use an external plug, I'd go for the internal, save money and cut down on the inevitable complications of data transfer through a USB or similar.
Oh, and if your chosen model comes bundled with an operating program, look for one with Ahead Nero burning software, instead of Easy CD creator. IMHO Nero is streets ahead of Easy CD these days in terms of ease of use. This is one case where you want software bundled so it is specifically optimised for the writer. It saves a lot of hassles compared to trying to match a shrinkwrapped unit to a cheap CD from BKK or Johore, if you understand. Not that any of us would do this, of course.