Do you know who makes it? If not:
* Plug your card reader in and get out of the installer program.
* Download USBView from http://www.ftdichip.com/Resources/Utilities.htm and run it.
* In the left hand pane, you'll see a list of your usb devices. One of them will be your card reader. If there isn't a likely looking candidate, unplug as many USB devices as possible and look again. When you've found a likely candidate in the lefthand pane, click on it.
* Now in the righthand pane, you'll see information about that USB device. Look for idVendor in the left hand column - in the righthand column, you'll see an associated code, starting with "0x". Google this and you should find out who the manufacturer is. Then have a google for a driver.
That probably took longer to read than it does to do.