Horizontal Text Scrolling With Refresh?

I'm writing application that displays messages from users. This messages are kept in external XML file and every time user post a new message this XML document is appended.

What I want to do is to display all messages at the bottom of screen. Messages have to slide horizontally in one line. To do that I used this code:

horizontalScroll.js:
var scrllTmr;
window.onload = function(){
document.getElementById('scroll').style.overflow = 'hidden';
document.getElementById('scrollme').style.float = 'left';

[Code]....

The problem with that code is that at 1/3 length of text it starts from beginning and this is wrong. The text have to scroll to the very end and then start to scroll from beginning again.

Another thing, that I'm unable to deal with is refreshing/reloading the content from XML file. What I need to do is to check if XML was changed/appended and if it was then I have to add this added message to text that scrolls horizontally and view it at the end of horizontal text. I'm pretty sure I have to use Ajax here. Also, if text from XML file will be added to horizontal text page cannot refresh and start scrolling from beginning, but instead of that if have to append horizontal text and continue to scroll showing appended message at the end.