If you are a serious Linux user, probably the first thing that come across your mind when shopping for a laptop is how compatible it is with GNU/Linux operating system.
Fortunately sites like The Linux Laptop Wiki, Ubuntu Linux Hardware Support and Mandriva Hardware Database provides a good starting point to find out about your laptop hardware compatibility with Linux.
As for my personal experience, I find out most hardware incompatibility ranges from unsupported 56k softmodem driver to unsupported hard-disk controller which i consider as the worse case scenario.
So please bear this in mind that not all laptop are 100% compatible with Linux. Do ask around, and check for its compatibility status before you finally made a decision to purchase a new laptop.