Hi,
I am a big Audio Book listener. I was a little confused by what you asked. If you borrow an audio book from a library, isn't it already in CD form? Or are you borrowing a cassette. But you said "rent".
Anyway,
If you "borrow" a cd from a library, it is a time consuming, but easy method to convert to MP3. If you are "downloading" from an online library, it is a different procedure.
First, if you "borrow" a cd from a library, most of them are in normal format that you could play in your car's cd player. However if you want it on a MP3 player, the method I have found is this:
Download "Itunes" from it's site.
www.apple.com/itunes/download/
It is free. It is primarily an Apple product, so make sure you download the PC version.
After you have downloaded it and got it working OK, then go to the "Edit" tab, and choose "Preferences". Under "Preferences" select the "Advance" tab. Now you will have another screen with three tabs, "General", "Importing" and "Burning", choose "Importing". On that screen, you will have a selection "Import Using" with a drop down choice. Choose "MP3" encoder. I usually also choose "On CD Import" the "Ask" setting, just so I can control it. Click the OK button to get out of the Preferences.
Now you can put the CD into your computer and Itunes will ask if you want to import it. Confirm this, and Itunes will not convert each track from the CD to an MP3 file.
However, here comes the time consuming part.
Each CD will convert with the identical track names and numbers. SOOOOOOOO, if you have multiple CD (which all audio books are) then you must work around this. I have found two methods: One, I transfer the files for each disk to a separate directory. I use the PC's Windows explorer to create a directory for the book, then subdirectories for each disk, i.e., Disk 1, Disk 2.... Make sure they are in Alphabetical order, because the directories will transfer in alphabetical order. Then, using windows explorer, copy each disk's files from itunes folder to the appropriate folder. (if you don't know how to do this or can't find out how, send me a personal message and I'll explain it.) After you have transfered each disk's files to the subdirectory, go to Itunes and delete all files with Ctrl-A and Del key. Send to waste basket, DO NOT KEEP IN ITUNES. Repeat this with each disk in the Audio book. When you are finished, return to Window's explorer and copy the individual folders, with the audio files, to your MP3 player, IN ORDER. DO NOT SCRAMBLE THE ORDER.
I have several MP3 players, and each one will play files different. One of them plays the files in the order I transfer them, another plays them in the order of the track numbers, and another one plays them in the order of the track Name. If you know which way your's plays files you might could skip some steps.
Now, for the other method I found:
As you download each disk into Itunes, do not delete them. However: After the first disk, the second one will have the same track names and numbers. I do the following:
Starting with the First Disk, I select all files, (ctrl-a) then right click on my mouse and choose "Get Info", find the field of "Disc Number" and place the appropriate "Disc" number in there to keep everthing clear. (I also enter the Artist [author] and Album [novel title] in to keep things clear. ) Then click OK. Now, at least you will know which disk it is from. On each subsequent disk importing, enter the disk number, however, you will need to go through each track individually and rename the track Name and Number sequentially. Depending on how many tracks per disk and how many disks, this could take days to finish. Several audio books have 99 tracks per disk, and 8 or more disks. Maintaining track integrity is confusing. When this process is finished, you can use window's explorer to transfer all the tracks to your MP3 player, or burn it to a disk [for personal and temporary use only.. that is for copyright issues.]
If you are not willing or able to do these proceedures, I have two suggestions, the first is the simplest, just play the borrowed CD in your car's cd player or in an appropriate portable CD player. The second is see if your library by chances has MP3 audio disks to borrow. Most libraries DO NOT, but you could always check.
Technically speaking, I know copying the CD's violates copyright issues, however, for personal use during the lending period is probably not going to get you into trouble. Any problems, feel free to send me a personal message.
The other method, downloading from Library sites using Overdrive Media is totally different. If this is what you are doing, send me a personal email, and I'll work with you. Personally, I haven't done this methods, but I have downloaded audio books that I have purchased from the web, and have a little knowledge.
Good luck from a fellow audio book fan.
Alyson