[jQuery] Can't use jquery_1.2.1.js together with json.js?

[iWorm]

Hi,
When I include the two js file together using
<script language="javascript" type="text/javascript" src="jquery.js"></
script>
<script language="javascript" type="text/javascript" src="json.js"></
script>

I found that I can't use jQuery.get() function to get a web page. The
jQuery Ajax doesn't work;

If I do not change any js code except delete the line<script
language="javascript" type="text/javascript" src="json.js"></script>,
all my code works good.

Anybody has ideas?

Thanks.