I have a Fujitsu Lifebook N6010 with an integrated card reader. It read up to 2GB SD cards just fine, but wouldn’t read 4GB or 8GB SDHC cards – even worse, it would ask me if I wanted to format the card!
The card reader is a Texas Instruments PCIxx21, which I understand is a fairly generic card reader used by many laptop manufacturers. I found this webpage which showed how to upgrade the driver. The only thing I did slightly different was to use this later hotfix for support of cards larger than 4GB. Now it reads my 4GB and 8GB SDHC cards just fine!