Web designing shouldn't be checked using one browser, for it could appear differently when viewed in other browser. You also must be knowledgeable of the issues that could affect your design. Like the CSS issues within IE6 and IE7.For pages that works perfectly with IE, you could an IE View, a Mozilla extension that will allow the current page or links to be opened in Internet Explorer. More details about these, on the link below.
Link: CSS compatibility in IE7 vs IE6; CSS