Try this.
If one does not exist add a css file to yor project and add the following css code to that;
div.fileinputs {
position: relative;
}
div.fakefile {
position: absolute; top: 0px; left: 0px; z-index: 1;
}
input.file {
position: relative; text-align: right; -moz-opacity:0 ; filter:alpha(opacity: 0); opacity: 0; z-index: 2;
}
now this is your fileupload control with link button; html:
<div class="fileinputs">
<input type="file" class="file" />
<div class="fakefile">
<input />
<a href="">Upload File</a>
</div>
</div>
as you see i have added anchor(a) a tag instead of a linkbutton since they will have both same apperance.but if you want you can change
<a href="">Upload File</a> with
<asp:LinkButton ID="fff" runat="server" Text="Upload File"></asp:LinkButton>.
do not forget to add css reference in you page as
<head>.....
<link href="StyleSheet1.css" rel="stylesheet" type="text/css" />
.....</head>
Resource is http://www.quirksmode.org/dom/inputfile.html