If you have an external hard drive kicking around, you could use Carbon Copy Cloner to copy the contents of your current hard drive to the external. Make sure it's bootable, then replace the hard drive in your MacBook, boot from the external, and Carbon Copy Clone the contents to the new drive.
Any 2.5" SATA drive will do, as long as it's no thicker than 9.5mm. (most drives are 9.5mm)
20" C2D iMac, 21.5" i3 iMac, MacBook, AEBS, 8GB iPod nano, 16GB iPhone 3G, 16GB iPhone 4, 40GB AppleTV x2, 16GB iPad 3rd gen