In Windows, open Control Panel -> Networking, then open the Properties box for TCP/IP. Check “Obtain an IP address automatically.”
It’s just as easy in Linux; the only hard part is that every distribution puts the configuration file in a different place. In Red Hat and Fedora, edit /etc/sysconfig/network-scripts/ifcfg-eth0 as follows:
TYPE=EthernetDEVICE=eth0 BOOTPROTO=dhcp ONBOOT=yes DHCP_HOSTNAME=stinkpad
On Debian, edit /etc/network/interfaces as follows:
auto loiface lo inet loopback auto eth0 iface eth0 inet dhcp
You may wish to use a graphical configuration tool. On Red Hat and Fedora, use system-config-network. KDE and Gnome have their own GUI configuration tools (as does practically every Linux distribution), so you won’t be short of choices. Another option is netGo, a system-independent network configuration utility that lets you create profiles for easily connecting to different networks