I got this error message. Magento Url "http://localhost:8080/magento/" is not accessible

A quick google on this one brought the answer in this link:

http://www.magentocommerce.com/boards/viewthread/8785/

The answer is to make a subtle change on line 139.

Hi, to install 1.0.19870.1, please edit app/code/core/Mage/Install/Model/Installer/Config.php on line 139, replace:

From
$client = new Varien_Http_Client($url. $prefix);
to

$client = new Varien_Http_Client($url.'index.php/' . $prefix)

More details at the link.