Server Storage

I am uncertain why you would bother with a NAS if you are running a full computer anyway. The advantage of the NAS is to have network available storage in the home without the need to run a full computer. If you do need the server for active directory, policy control, and NTFS security etc, then just mount the hard disks into the computer and sell the NAS, then you would have no speed issues. But I doubt you would need this set up for the home. My advice is to ditch the old PC and just use the NAS. If you are running a Gb network and are not constantly transfering 10Gb+ files it will be fine

it's possible, you could map the NAS to the server and then not share the servers hard drive and share it as the NAS hard drive, but it's pretty pointless, since you'd get better speeds just accessing the NAS serperately, but I agree with scifi, if you wanted you could just pull the hds from the nas and stick em in the old PC and just share them that way. You might get better speeds that way than with the NAS seperately because the server will be able to allocate resources better and feed the information faster, but only so long as it's not got too many things running on it. The benefits of a NAS is that it's just for storage (small bit of ram and processing power to allocate data), while a server is for administration over other PCs. So having a server and a nas seperately might be better if your server will use up a lot of it's processing power doing admin work or using other programs.