Hello,
I have located a download of Internet Explorer 5.2.3 (the latest Mac version) at:
http://browsers.evolt.org/download.php?/ie/mac/5.2.3OS_X/InternetExplorer523en.dmg
You should be able to download it from one of the 3 sites linked on that page (3 different download links).
If you need it in a language other than English, you should be able to find those at:
http://browsers.evolt.org/?ie/mac/5.2.3OSX
Keep in mind that while this should run fine on your Mac, that the Macintosh version of Internet Explorer never supported ActiveX.
ActiveX is the technology that makes many websites require Internet Explorer. This is a method of allowing the website to control your computer, and perform functions that would be more difficult to perform using plain HTML.
Unfortunately, ActiveX is used by many sites that don't realize the importance of making a site universally compatible.
Many webmasters simply assume that since the majority use Windows, that there is no problem using "Windows Only" code.
Unfortunately, Microsoft has maintained tight control over ActiveX. So, there is no other browser that will work with it. If the sites you need use ActiveX, then you absolutely will need Windows and the Windows version of Internet Explorer to access those sites (even other browsers will not work with ActiveX sites when running under Windows - it must be the Windows version of Internet Explorer or nothing).
Some sites will work with other browsers, but have a detection mechanism in them.
Those sites can be made to work by simply changing the identification code that your browser provides that website. The previous posts have already detailed how to do that.
But, changing your identification code will not make a site function properly if it requires ActiveX.
Fortunately, the only portions of the site that should fail are those that use ActiveX.
I hope this helps you out. Good luck.