Installing multiple browsers

Since I figure Im not the only web developer in these forums I thought it would be a good place to ask.

What is the best way to install multiple versions of browsers on Windows system. I know I found a site a while back that had packaged different browsers in their own folders (more like linux style).

Now with FF2 and IE7 I want to be able to test my sites on those as well as IE6 and FF1.5.

If the particular browser lets you click Advanced in the install process and specify a diff path (like you suggested), but if memory serves MS doesn’t let you do that with IE.