The RS-232 DF1 full duplex driver usually works fine with USB-RS232 converters, especially a couple of Belkin and Keyspan models that A-B has tested.
What doesn't work (and yes, there have been many detailed threads about why) is the 1747-PIC driver. It doesn't work with the PIC itself, the 1761-NET-AIC, or a straight cable.
I saw a 1747-UIC USB/DH485 converter at Automation Fair last week, but it was a prototype and I don't know when they'll be able to make it a product (usually 3-6 months after AutoFair at the earliest !), so if you absolutely require DH-485 functionality you need a 1784-PCMK card and -PCM4 cable or a 1747-KE converter module for the SLC chassis.