hum i dont think that network drivers are safer than internal shared drivers.
Due to some "restrictions" on their configurations, netdisk can have even weaker security against pc drivers. Please compare security options of your netdisks (that you want to buy) and regular shared disks (*nix, Windows)
Also please be aware that some ISP doesnt like that you act as a big server node and eat a lot of BW. Also There is some ISP that has specific clauses to disallow more than ONE computer connected on their links.
Ahn, you will say "they cant see, because im have a NAT firewall"
and i will reply "yes, they can". Like in your config, with mixed O.S. is a piece of cake to know there is more than one. Just some concerns