How would I go about transferring this amount of data from a working (but dying) external usb drive to another. I guess I could copy & paste but there must be a more practical way.

You could use a batch file. "So won’t you give this man his wings What a shame To have to beg you to see We’re not all the same What a shame" - Shinedown

except a batch file is just a series of commands, and this batch file would just be commands to copy and paste anyway. is this a single file, or a bunch of little ones? I've had bad luck transferring huge amounts of data if it's spread across thousands of files. For example, if i drag and drop my entire music library, i usually lose about 30% of the files along the way. I have much better luck moving less than 1GB at a time. if the drive is dying, suck it up and move the files manually. as soon as possible.

If using two USB drives try to separate them by using different controllers too. Normally, USB controllers will serve two or three USB ports. So use ports that are NOT side by side. If the drive is failing I would recommend removing from the enclosure and connecting internally. Faster transfer that way and the drive should run much cooler. Heat is probably the biggest killer of external drives. BTW, if you have a 1TB external and have anywhere near 1TB of files stored on it that may be the issue itself. How is the drive formatted? FAT32 or NTFS? There is a reachable limit on the number of files in a folder under FAT32. Exceeding it will probably result in CRC (cyclical redundancy) errors.

I'd use ntbackup with system state. It is on the CD if you didn't already install it. It is a good free way to save important data and programs. Then when you get your new drive they also come with a program to copy the drives. "Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10