Linux and Mac are both unix based and they both can do amazing things. I personally use linux as my server which I build DHCP, DNS, Iptables, Postfix with Dovecot for email, Mysql, Samba, Apache for web server and Asterisk PBX..... Other than that, I use Windows 7 for connecting my TV and Home theater. My old laptop has windows xp and fedora 14 dual boot. It works very well.
If you guys really think about it. I can build my server by using Mac but the cost is much much higher. My Dell server was around 300 dollars but the cheapest Mac server would be over 2 grand.