Can I run different browsers under OS 10

Part of my job is to test test how our corporte web sites will look and act with different browsers and operating systems. This means I have the only Mac in the department. A G3 iMac running OS 9.0.4 currently. I have IE 5.0 and Netscape 4.7 runningon it.

I want to upgrade to OS X so that I can test the newest versions of IE and Netscape (heck even Opera)

Can I still run all of the older browser versions alongside the newest ones on the one Mac?