Well, I've always had great luck doing the following:
1. Buy new laptop hard drive
2. Buy an external USB enclosure that will work with said hard drive (these can be gotten pretty cheap, like $20 or less if you shop carefully)
3. Boot laptop with a Linux boot disk (USB or CD)
4. Use 'dd' to clone internal HD to external HD
4a: the free bootable ISO "CloneZilla" will make this even more painless
5. Swap the hard drives
6. At this point, the laptop should boot as before, but with a large chunk of un-allocated space on the hard drive
7. Now, you can either format the blank space as an additional partition, or expand the boot partition to take up the empty space
8. And if anything goes wrong with Step 7, you can always start over
1. Buy new laptop hard drive
2. Buy an external USB enclosure that will work with said hard drive (these can be gotten pretty cheap, like $20 or less if you shop carefully)
3. Boot laptop with a Linux boot disk (USB or CD)
4. Use 'dd' to clone internal HD to external HD
4a: the free bootable ISO "CloneZilla" will make this even more painless
5. Swap the hard drives
6. At this point, the laptop should boot as before, but with a large chunk of un-allocated space on the hard drive
7. Now, you can either format the blank space as an additional partition, or expand the boot partition to take up the empty space
8. And if anything goes wrong with Step 7, you can always start over