A pedantic point:
'Explorer' is the program which helps you navigate around your PC (e.g. by opening folders and moving files between them). You seem to be referring to 'Internet Explorer', which is a web browser.
The vast majority of web site will open perfectly well in any version of Internet Explorer (well, from IE 6 onwards, anyway). If you don't want to upgrade, there's no real reason to do so. IE8 is theoretically more secure than earlier versions of Internet Explorer but the threat levels probably aren't really that different anyway.
Most of the 'regulars', here in AB's Technology section, don't use Internet Explorer at all. The world's most popular browser (where 'popular' is defined by choice, rather than by lethargy) is Firefox:
http://www.mozilla.org/en-US/firefox/new/
That's what most people around here (including me) use but Chrome, which is the second most popular browser worldwide, also (deservedly) has many fans.
Forget Internet Explorer and switch to Firefox (or Chrome) today. You won't regret it!
Chris