http://forums.cnet.com/5208-6122_102-0.html?forumID=44&threadID=228374&messageID=2374530

I'll copy in some text that I found 6 pages into a google search while researching this for myself (with 3 years of email history at stake) it was posted in 2002 on a google support page (?!)... I found my files in a different location though. I right-clicked START and selected explore. At the bottom of my list was a folder named AOL SAVED PFC. inside I found my last (just replaced) AOL version and opened it. Then I used the text below to tell me what to do... 
" The .pfc files mentioned before don't exist. You need to
create them. Start by double clicking on the MY COMPUTER icon on your
desktop. Double click on the C drive, then double click on PROGRAM
FILES. In this folder, you will find an AMERICA ONLINE 7.0 Folder
(however, there may be more than one). Double click on that folder. 
Inside of this folder, you will find an ORGANIZE folder. Drag this
folder to your desktop to make working with it easier. Open the
ORGANIZE folder from your desktop and search for a file that is very
similar to your screen name. It will contain only the letters of your
screen name, and the last few letters may be separated by a period. 
The file you are looking for is NOT a .arl file or any other file
extension. If you find more than one file that is labeled as your
screen name, select the largest one. You can find the size of the
file by right clicking on it and selecting properties.

Once you find the file that is labeled the same as your AOL
screen name, right click on it and select RENAME. Rename this file to
whatever you want, and add ".pfc" to the end of it. For example:
Myscreenname.pfc. You have now isolated your filing cabinet and set
it up so that AOL can read it.

Open your AOL 5.0 software. Click on FILE from the menu bar
and select OPEN. Navigate to your desktop, double click on the
ORGANIZE folder that you dragged to the desktop earlier, and double
click on your new .pfc file. This will open your list of favorite
places and email. You should be able to drag and drop these files
back into your filing cabinet from there. "

http://email.about.com/od/aoltips/qt/et040706.htm

Backup or Copy Mail in Your AOL Saved on My PC Filing Cabinet
To backup mail in your AOL Saved on My PC filing cabinet: 

Search your computer for a file called "(your AOL screen name).abi". 
If your screen name is "myscreenname", for example, search for a file called "myscreenname.abi". 
You should find it in a folder called organize folder. 
Select Edit | Copy from the menu of the Explorer window. 
Open the desired backup location (a CD or DVD, another hard disk, a network location or a USB stick, for example) in Explorer. 
Select Edit | Paste from the menu. 

http://www.pctoday.com/editorial/article.asp?article=articles%2F2006%2Ft0406%2F27t06%2F27t06.asp