For a reasonable amount of money, I suggest it's well worth getting yourself a copy of Acronis True Image. You can buy version 8 for only 12 pounds at click here.
This will enable you to create an exact image of your entire system as it stands now - OS, software, applications, drivers, etc. - and restore it all to your new hard drive.
You'll need to consider what media you will copy your image on to, and this will depend on how big your system is. You could consider a pen drive, DVD or external hard drive (if you have one).