Replacing hard drive

You will need to replace the OS, remember to back up your files first .

 

If you can some how get the new hard drive do show up in Disk Utility, you can use a program called Carbon Copy Cloner to make an exact copy of your original HD to the new one. I'm assuming the original HD is in good working condition and you just want a larger HD? You can using something like an external USB and/or FireWire case.*

Otherwise, yes, you would have to reinstall everything, the OS, apps, etc.*

Like Eraserhead said, I would make a backup of anything important before you do anything.*