Please remember to use WikiFormatting, preview your post and Cc the maintainer.
http://packages.macports.org/php5 is not the URL the tarball was downloaded from, but rather the URL where port(1)
tries to find pre-built binaries. Since there aren't any for the php5 port MacPorts will fall back to building from source and starts downloading the source tarball, which apparently fails for you. The file you got instead of the source tarball appears to be HTML, which is commonly caused by misconfigured DNS servers or mirrors. See MisbehavingServers for some pointers on what to do in those cases.
Also, this bug report is useless without the main.log, so please attach it, if you can. Feel free to re-open if the problem persists and you can provide a main.log.