Adding the COM1 port (if you want to):
"U17" is either a LGS GD75232D or HT6571. A 75232 is a common chip. You simply put one in "U10" and add the connector header.
The connector CN18 is pinned exactly like any serial card, just plug it in and go!
Caps are not needed for it to function, unless you are worried about FCC or long cable runs.
You may find the chips on dead serial cards at the swapmeet. www.digikey.com
This would be great for uploading MP3's.
Pic of cable pluged in:
USB ZIP drive would be better, but this is nice.