NAS or network shares under Windows?

Hello,

I've a second computer (running Windows 7) that I would like to turn it into NAS, to store all my data and make them available on my network.

I looked on the web and I found different NAS projects (under Linux) as FreeNAS, NAS4Free and OpenMediaVault that I was thinking of using it because it can make NAS backups on external hard drives formatted in NTFS.

But I've a question: does there's a difference between using these NAS systems and create network shares under my Windows 7?

My goal is to store data and make it accessible on my network for my computers and devices: does network shares under Windows can be a good solution for me?

If not, what would be the benefits of using one of these NAS systems instead of network shares under Windows?

Thank you for your help :)
Chris