We tried a few of the "big company" combo SAN/NAS devices and found that they... well suck. They can't do all things well. They can either do Windows well, or UNIX well, or SAN well. But not all things well no matter what the marketing literature says. It is also very simple to end up paying a whole lot of money by the time you get the pieces and parts put together.

What we ended up doing is getting a SATA2 SAN that supports 5 simultaneous connections over gig copper. We connect to it over iSCSI. We have:
- Mail Server mounting via iSCSI
- DB server mounting via iSCSI
- Windows file server that acts as a NAS, but is saving to the SAN via... yup, iSCSI
- LINUX NFS server that acts as a NAS, but is also saving to the SAN via iSCSI

This ended up being way simpler and much more cost effective. And yes you can run SAMBA on LINUX, but this is way easier to manage and maintain.