<p>I want to change the Text of the browse button in the FileUpload Control (System.Web.UI.WebControls), instead of the [Browse...] text I want to use [...]</p>

This isn't technically possible for security purposes, so the user cannot be misled.
However, there are a couple of workarounds, although these require working with the raw HTML rather than the .NET server control - take a look at
http://www.quirksmode.org/dom/inputfile.html
for one example.