Not too long ago I found myself forced into troubleshooting a front end issue in Internet Explorer and the first thing I did was poke around IE's ham-handed developer tools. It didn't take long for me realize that the tools were worthless and get frustrated. Luckily I decided not to break the computer I was sitting at and instead ended up Googling my way to a nifty solution.
There are pieces of Firebug functionality that Firebug Lite does not replicate, but in my quick usage the only things I noticed missing were the "Layout" tab that lets you see positioning and size rules for elements and the "Net" tab that allows you to monitor HTTP requests made throughout the page render. Other than that, Firebug Lite seems entirely functional and it can provide you with the context you need.
Someday this will save you.