Important note: Remote desktop is only included in the Professional,
Business, or Ultimate versions of Windows. Home editions do not have remote
desktop.

To get to the configuration page, you can either right-click the Computer
icon and choose properties, or you can type in system into the start
menu search box, and then find the entry for System.

Now you’ll want to click the Remote Settings link on the left hand side:

Now you can finally turn it on:

To connect from another Vista / Win7 PC on the same network, click the
bottom radio button. If you need to connect from an XP/2k machine, click the
“Allow connections from computers running any version of Remote Desktop” radio
button.

Don’t worry about setting up firewall rules, Vista or Windows 7 does that
for you automatically.

Note: This should work for both Windows 7 and Vista.