The C drive is easily cloned. You can use any number of tool. The HIRENS disc is a good source of tools for this type of application (although vet the source of the ISO as they aren’t all legit. You can double check the MD5). You wouldn’t need much prep to clone partition.
The tricky part will be in trying to clone the 6 disc RAID 5 array. You will need a destination large enough to take anything you have on this drive. For this as it’s not the system drive I would highly recommend doing a backup and restore using something like NT Backup, backup exec etc.
You are going to face problems though if you have applications installed onto the G drive instead of just files. In which case you are going to need to do a disc level backup/clone using a tool such as ghost or acronis and have an identically setup system ready to receive the data.
With something like it is going to depend on what exactly is on each drive as how you would do this. Remember, Google is your friend.