I am planning on building a small form factor PC but it will need RS232. I don't know for sure if there will be room for an add on card for the RS232. Is there a usb to RS232? If so, will it work as good as an add on card?
Check out this link: TRENDnet USB to RS-232 . I do not personally own one, but I have used them at my job and they seem to work pretty well. You may have a driver issue, depending on the OS you will be using, but for the most part it works.