Anyways, to respond to the OP.
I've set up hand full of Windows servers (Windows severs 2000, 2003, 2008, 2008 R2 and 2008 Server Core) and I've set up even more *nix servers (Numerous flavors of Linux, FreeBSD and OpenSolaris) with my favorite always being FreeBSD.
You'll find most things (once you get comfortable being a server admin) are typically easier to do in *nix most of the time on a server level (kind of backwards from ease of use on the desktop side).
IE, i can setup OpenVPN, OpenSSH, transparent squid caching, BIND DNS, PF (or iptables if on Linux), DNSMasq (or DHCPd), clamd (clamAV), apache (with mods for fastcgi, php and perl), Mysql, etc all from the commandline with little more then 1 or 2 commands for each. Doing the same on Windows Server series would require me fumbling around with less then intuitive GUIs and setup wizards (server series is notorious for having you use setup wizards)
Either way, whatever route you decide to take, heres some things you can do.
- Set up a local icecast server to have a house hold radio station over IP (or if you set up NSV you can create house hold TV stations over IP aswell)
- Set up a NAS (to easy on windows with SMB but sucks balls for movies in my experiences)
- Set up a caching proxy to ease load on your bandwidth and accelerate web site load time for all computers in your house
- Set up a recursive (caching) DNS server (BIND or DNSMasq) to cut DNS query time from ~58ms to about 1ms over lan or <1ms on the local machine
- Use IPTables (on linux or PF for FreeBSD, IPFW for Solaris or the "routing and remote access setup wizard" on windows server series) to set up NAT routing so your server can act as a router for your home network and setup a DHCP server to issue out IP addresses and such
- Set up a centralized back up server (rsync on *nix hosts and something like robocopy (over SMB) on windows)
- Set up OpenVPN so you can VPN into your home network anytime from anywhere over a secure channel of communication
- Set up OpenSSH so you can do the same thing as OpenVPN but on a more niche level
- Set up a database server (mysql, postgre, etc) and use it to keep track of random things (i use one to manage a todo list (overkill inorite), to keep track of people borrowing my shit and as a personal invoice like service for my bills and who owes me money)
- Set up an IDS/IPS (i usually hack my own together by piping tcpdump through custom filter progs i write)
- Set up a PXE boot environment so computers can boot over the network via your server
- Buy a wireless card and turn your server into a wireless Acces Point (AP)
- Set up a captive portal system so wireless users have to agree to a disclosure (or view grotesque imagery as i have mine set up) or provide login credentials (via a web portal, that authenticates via a RADIUS/KERBEROS AAA server and keeps track of usage time), I've had good experiences with both the OpenBSD Packet Filter (simply PF) and CoovaChilli when setting these up
- Oh yeah, probably one of the simplest things you can do is set up a NTP server to syncronize all the computer clocks in your house
When it comes down to server/sysadmin your limited only by your creativity and will to do something.
EDIT: awwww man
i didnt even get to double post like an asswhole because Goatboy responded to fast