Yes, the normal serial port does have 2 power pins, but not much power. Enough to power the very small number of chips, laser diodes and receivers in a mouse. Certainly not enough to power a CD drive. USB stands for "Universal Serial Bus" (sorry if it's granny suck eggs time). Serial data goes down the wire 1 bit at a time, hence the name. Parallel data (to your printer or scanner, for example) goes 8 or more bits at a time, hence is 8 or more times faster. The drives in your computer also communicate with the processor, etc using parallel architecture. USB is fast, but nowhere near as fast as IDE or SCSI (used to talk to your drives).
I see your options as follows:
1) external drive - slow because of serial nature of data. Also, you will have to lug around yet another power supply with you to power it.
2) replace your existing CD-ROM drive with an internal CD-R (or CD-RW - more later). This is likely to be V expensive, as are all notebook goodies as micro-miniaturisation costs oodles of dosh.
3) assuming you have a desktop PC, use laplink (see another recent thread on this forum at
http://www.pprune.org/ubb/NonCGI/For...ML/000530.html ) to transfer your data onto your PC and from there to a CD-R or CD-RW. For this you need to buy a drive for your computer (much cheaper than for a notebook) and a bit of 'lectric string to hook the 2 computers together (again, see the thread mentioned above). The downside of this method is, it is a 2 stage process, therefore slow.
Now, as to the benefits of CD-R and CD-RW...
http://www.pprune.org/ubb/NonCGI/For...ML/000487.html
There you will see the relative merits of CD-R and CD-RW discussed. The bottom line is, use 1 or 2 CD-Rs to back up your system and CD-RW to back up your data.