What is the quickest and best way to copy a 500 GB drive?

Use TeraCopy.

TeraCopy is a compact program designed to copy and move files at the maximum possible speed, providing the user with a lot of features:

• Copy files faster. TeraCopy uses dynamically adjusted buffers to reduce seek times. Asynchronous copy speeds up file transfer between two physical hard drives.
• Pause and resume file transfers. Pause copy process at any time to free up system resources and continue with a single click.
• Error recovery. In case of copy error, TeraCopy will try several times and in the worse case just skip the file, not terminating the entire transfer.
• Interactive file list. TeraCopy shows failed file transfers and lets you fix the problem and recopy only problem files.
• Shell integration. TeraCopy can completely replace Explorer copy and move functions, allowing you work with files as usual.
• Full Unicode support.
• Windows 7 x64 support.

If you're using Windows 7 or Server 2008, try robocopy.

cmd > robocopy c:\ d:\ /s

robocopy everything from C:\ to D:\ including subdirectires

Use Fastcopy.

FastCopy provides a faster way to copy, move or delete large numbers of files. It automatically selects an optimized method depending on whether the Source and Destination directory are on the same or different hard drives, and performs read/write operations without using the O/S cache. In addition to simple copy and delete operations, the program also supports advanced methods that allow you to synchronize files based on their date and size. Other features include customizable buffer size, preview of file actions, adjustable speed control, command-line support, file verification and advanced file filtering. FastCopy supports Unicode and long file names. Standalone software, installation is optional.