Summary: I bought two of these cards to use in new HP computers running Windows 7 Pro, but finally had to abandon them. They caused the computers to lock up every few minutes and become completely unresponsive. I suspect the drivers are not compatible with Windows 7, so be forewarned if you are using a computer with that operating system.
Summary: Have a low-budget server running 2008R2 for a small business running 15 computers. Need a port to connect an external modem for a fax program. Given that this card with 2 serial ports was only $10 more than cards with a single serial port, it was definitely the best deal. Card worked with no issues. Definitely worth it.
Summary: I've been testing software at 115.2 KB using two USB to Serial converters. I tried using the Startech board to replace my existing USB to RS_232 setup, but the driver software didn't work well with the application I'm testing.
PEX2S553 Works fine with one card. fails with two cards
27 July 2013
Summary: I needed four serial ports. I installed both cards, installation went well, Windows 7 Pro 64 bit recognized both card using the 64bit drivers, no conflicts, no errors in log file. Brand new HP I7 desktop, 10 gigs memory. All four ports were non responsive. Once I took one of the cards out, the two ports on the remaining card worked fine. I am wondering if only one card can be used at a time.