Am I right in thinking this text is generated on installation? I have edited the files above, uploaded them and tried numrous times to re-install SilverStripe and I still cannot get rid of it.
I am in the process of going over the whole default installation to completly remove all mention of SilverStripe and take out anything that is not needed for my clients. I will be writing documentation for this and will share it with everyone once done.
$homepage->Content = _t('SiteTree.DEFAULTHOMECONTENT', '<p>Welcome to SilverStripe! This is the default homepage. You can edit this page by opening <a href="admin/">the CMS</a>. You can now access the <a href="http://doc.silverstripe.com">developer documentation</a>, or begin <a href="http://doc.silverstripe.com/doku.php?id=tutorials">the tutorials.</a></p>');
There are two other default content items there for the about us and contact page that are created on install.