Yep, that's the link - just change {$http_location}/ to
www.mydom.com/xcart/home.php
Not sure why you would want to, but that's all you need to do.
And Yep, that's exactly where I mean. Why doesn't that seem like the place? Unless you have hard coded the text into your skin1/customer/main/welcome.tpl template, which I very much doubt, just like most of the text on your site, it is stored in the database, and accessed through Languages in your Admin section.