Just like any trade, a developer needs the right tools for the job. Some may argue what those tools are but here is a short list of my preferred tools when working on any web site or web based application.
Article by Gary Larocque
Multiple Browser Installs:
A pre made install package makes installing multiple versions(IE v3.0 - v6.0) of IE less of a manualprocess than multiple versions of Firefox.
Tredosoft's Multiple IE installpackage