The standard PC card slot is much slower than an external USB 2.0 card reader unless
you use a cardbus reader such as the Delkin Cardbus 32
. These are MUCH faster.
If you are using a PC then you'll get drivers with the adaptor that will work with your OS. For Mac, it's still very irritating that they don't have a 10.4 driver available yet, only up to Mac OS X 10.3.9 are supported at the moment.