Welcome to the SevenForums! rdcanlas
The first question I have here for you would be the make and model laptop. The information on that will provided the necessary system requirements as far as the OS. If this is on an older model that saw XP preinstalled you would then need to find at least Vista updates in order to see a working install of 7 go on. The two versions are close in driver
For seeing a working dual boot on a laptop the guide gregrocker pointed is your best resource. That will take you through two different types of installs one where XP goes on first followed by 7 or the second for seeing XP installed after 7. For the later the 7 mbr information will need to see a startup repair following the XP install due to the newer boot loader with the newer version of Windows.
Most newer boards automatically allow the XP installer to detect and install on sata drives unlike the old Socket A, 939 for AMD and old Celeron, Pentuim boards. The newer onboard sata controllers allow for this. The make and model laptop however will indicate which versions are supported.
Another thing to consider is how large is the drive the laptop came with? If this is old until only seeing an 80-120gb drive you may want to consider going with a larger, faster drive since prices have fallen sharply in recent years. A good 500gb drive for a laptop can be found for under $50 if needed which would allow plenty of space to work with for running two versions of Windows and all programs.