You could partition it into two or three parts for ultimate useablility.
1 300GB partition for a complete backup of your 250GB HDD
1 500GB partition for general storage
1 200GB partition for new programs/games
Can I switch some seldom used programs on my C drive there, freeing up more space on my main drive, and will this allow my system to operate more efficiently?
Yes and no.
As far as I know you cannot just 'move' a program from drive to drive, but you could uninstall it and reinstall it on your new one.
If not, are there any other uses for this new drive?
Sure there are many used for a hard drive, and I'm sure patio will agree, they make great coasters, door stops, bricks for houses...
Seriously though, the extra 50GB on the first partiton is for extra space for other types of backups and also a page file.
Because you will only be storing, say, a ghost image on the 300gb partition which can be copied sequentially, as there is nothing there...yet. The extra space it has left for a page file is the most ideal conditions you can have. Contiguous free space
