I have download the theme Red_Hat fromhttp://t-tech.org/, but was wondering if anyone knows where I can get this in english?

Thanks in advance!

Don't know where you can get an English version, you'll have to ask the people at t-tech.org.

It should work as it is, with three minor changes to the theme file

<td id="headerbanner">
<{if !$xoops_isuser}>
<form action="<{$xoops_url}>/user.php" method="post">¥í¥°¥¤¥ó̾
<input class="boite" type="text" name="uname" value="username" size=12 onMouseOver="this.focus();" onFocus="if(this.value == 'username') this.value = '';">
¥Ñ¥¹¥ï¡¼¥É <input class="boite" type="password" size="8" name="pass">
<input type="hidden" name="op" value="login">
<input type="submit" class="boutonvert" value="OK">
&nbsp;&nbsp;¢ª <a href="<{$xoops_url}>/register.php">¿·µ¬ÅÐÏ¿¤ÎÊý¤Ï¤³¤Á¤é¤«¤é</a>&nbsp;&nbsp;
</form>
<{else}>

Just replace the Japanese characters with English ones in the order of Username, Password, Register.

The rest of the them in the theme and css files are all comments in Japanese. You could simply replace them. Just grab a copy of the default css and theme files, compare and replace. You will have yourself an English copy.

[edit]WIKI has an excellent sample of the css file with comments and you may want to take a look
DefaultThemeCSS