Hmm.. Just to clarify..
Disc 0, you 1st physical HDD, has two partitions using C: & D:
Disc 1, the 80gb HDD you just added, is now partitioned and formatted, and showing as drive G:
What is taking up drives E: and F:?
Is the G: drive showing in My Computer as about 74-75Gb?
I would do the following:
1. Download and install Maxblast.
http://www.seagate.com/ww/v/index.js...00f5ee0a0aRCRD (scroll down and click on I Accept)
2. Use Maxblast to Clone the C: partition to the G: partition
3. Now turn off the computer and swap HDD positions. Make sure the jumpers on both HDDs are set to CS (cable select).
4. Turn on the PC and the new HDD should now be the primary HDD [C:] and boot from there with all your files.
5. Make sure everything copied over correctly and is working.
6. Wait a few days to give yourself time to make sure you no longer need the files on the old HDD.
7. Now you can use Maxblast or Windows Disk Management to delete the two partitions on the old HDD and repartition it as one and format. Then you'll be able to use the old HDD as D: for extra storage.