That's right, a lot of card readers don't work with 7. I installed a reader in one of the CD bays instead. Amazon has several for around $20, and they do work fine with even 64 bit 7.
The driver for the reader is usually in the firmware, built into the unit, and does not use a stand alone driver in the majority of units.
I know of at least two readers that work with 7, Sabrent and SIIG, but what kind of card you want to read should be researched before ordering a unit to install.