WP Child Theme to work on Windows Server 2003 Standard Configuration

Hello, I have been developing a WP based website internally for a company using a premium theme called Longpage (link: [login to view URL]). Unfortunately, in the middle of development it turned out that the theme does not display properly for Internet Explorer 8 users when the WP install is on a Windows Server 2003 Standard configuration, such as ours (not much choice in hosting for us here in China). The company that developed the theme is being totally unhelpful, despite their declaration that the theme should work on IE8 configs. Our current in-development website that uses the theme can be found at [login to view URL] I need a freelancer to create a WP child theme of the original Longpage theme in such as way as to display properly on all browsers, most importantly IE8, when the WP install is on a Windows Server 2003 Standard config. If a child theme is not possible, a remake of the original theme is OK. I look forward to hearing from you, Kind regards, Witold