I ordered one of these from Dontronics - apparently it has the best chipset to work with mounts/EQMOD. Has not skipped a beat for me so far.
http://www.dontronics-shop.com/usb-converters.html
Products Ordered:
Cat Number: US232R-10 #16139
Product: EasySync Premium GOLD USB-RS232 Adapter cable ( 10cm cable )
Item Price: AUD$45.91
Quantity: 1 Item(s)
Cheers,
Adam