Generally, yes it is. Depending on which mac you have and what you are trying to accomplish, there may be a few more steps involved, but nothing that complicated.....
After installing the new drive, use DU to format the drive to HFSExtended, then you can use either CarbonCopyCloner or SuperDuper to make an exact copy of your current drive's contents. Then open System prefs and change the start-up disk to the new drive and reboot.
If you want an entirely new install on the new drive, then just skip the copying part. Instead, boot up from your install DVD/CD, run the installer and choose the new HD as the destination, and after the installation is completed, switch the prefs and reboot.
it really IS that easy
