Is there any way in Finder I can get the window to show the amount of free space on a selected drive?

why not just right click on the drives icon on the screen an select "get info".

do you mean like this?

Finder -> View -> Show Status Bar

Sorry, I didn't know this was so old when I replied. I hope it was helpful anyway.

Go to desktop, click on hard drive, command+I or File ... Get Info.

Then you will see the info for that drive and listing the available space.