However if you have not used linux before, it is still a fairly steep learning curve compared to the point-and-clicky-ness of windows, (not as steep as it used to be, but prepare for some googleing)
Sounds Like any linux distro running samba (for sharing files to windows PC's) and maybe a webdav server (for sharing files over HTTP for when you are out and about over the net) may be what you are looking for.
I cannot compare to windows home server because I am not sure how that does things (have not had a play with it.)
//TrX