Windows 7 to a new hard drive

you can Ghost the drive to the new one, it's easy and you save all your files

Myself, I would do a clean install using the Upgrade disk.
The only draw back is that you will have to reload your programs and possibly some of the drivers.

If the drive is failing you may have some bad sectors and encounter a problem in doing a simple upgrade.

Method
1st disconnect your orginal HDD (leave in).
2nd install 2nd HDD and do a CLEAN install using your upgrade win 7 Disk

Method Using Upgrade disk to do a Clean install (from one of my prev post)
Do a Clean Install, But DO NOT enter your Key
Goahead and let windows 7 down load critical updates. Then:

Open regedit.exe with Start Menu Search and navigate to:
HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE
Easier - Just do a search for " MediaBootInstall"

Change MediaBootInstall from "1" to "0". (Double-click it and then enter 0 in the dialog that appears.)

Close RegEdit.

Open the Start Menu again and type cmd in Start Menu search to display a shortcut to the Command Line utility. Right-click this shortcut and choose "Run as administrator." Handle the UAC prompt.

In the command line window, type: slmgr -rearm

Then tap ENTER and wait for the "Command completed successfully" dialog.

You can now enter your registation number and activate Win 7.

With that out of the way, reconnect your 2nd HDD and using Boot menu (in bios, or usally F12 will booting) select your win 7 HDD. You should be able to see your orignal HDD and copy all your files and data to the new HDD.

Alternate - Just pull your old HDD out of computer and install in one of the $15 USB HDD enclosures and copy your Data to the New HDD.