The best thing to do is to manually copy data across to the new hard drive.
You can also use Windows own tools, e.g. click here, but it can be a long & tedious process. Moreover, if it crashes mid-way through, you may want to reinstall Windows afresh. Not worth the hassle imho.
Generally the area that contains data worth saving will be located in the 'C:\Documents and Settings' folders & subfolders, AND any other location/partition you manually saved data to in the past. The previous Windows & Program Files folders usually contain nothing worth saving, BUT it's always a good idea to backup & retain for a while - at least, until you get your new install exactly as you need it. G