The Size of Windows 7

Orbital Shark said:

The suggestion above would also take into account retore points, shadow copies and temporary files. If the OP is sufficient in the process of cleaning redundant files then you're correct 60GB will be sufficient.

I've seen in some cases that over 30GB has been freed up by deleting all bu the latest restore point.

So very true. This is often unaccounted for when setting up a primary partition. It's a rather double-edged sword in that it takes up a bunch of space and is of no use at all... until it saves you.

to the OP - while I may be stating the obvious to some - keep in mind that partitioning your 2nd 500GB drive into 3 drives is "logical" partitioning on the same physical drive.

You will need backups of all 3 assigned drive letters (E:\ F:\ G:\ ?) as you will lose it ALL if you have a physical drive failure.