Here's some more questions:
Do you have the OS CD, (Dell or XP, etc.)?
How long ago did you purchase the Laptop, did you purchase it from Dell?
Do you have a copy of ghost?
Do you want to completely reinstall the OS, or do you just want to copy the old instance onto the new Drive?
If you atleast have the OS CD from Dell (since there's atleast 2-7 CD's included with dell's) the OS CD will normally include enough drivers to get you online. Make sure to copy anything located in the C:/Dell folder, this will be most of the dell drivers.

More information necessary for suggestions