Multiple version of FF.. simultaneously

If I am a web developer, I would surely want my site to look good in all browsers. So I need to test that before my users do, right? This is easily possible for Firefox browser.

Say I have two versions of Firefox. One is the latest 1.5 and the other is old say 1.0.
1.5 is the one that I developed my site with. But I know that quite a few of my users are attached to 1.0. So I would need to install both the browsers on my PC. Thats where the pain starts. The moment I install the second version with all its shortcut, quick link etc. that version takes over. I found a solution to this problem on this site:

http://www.hiveminds.co.uk/node/3114.

They have detail explanation for a simple process and a complicated one. Now since I am a firm beliver in the KISS policy (Keep it simple, sir), I decided to follow the simple process. But I hit some roadblocks and had to find the workarounds on my own. So I thought why not streamline my steps.
1. I had FF 1.5 installed in c:\program files\......
2. So I installed FF 1.0 in my d:\ to be on the safer side. I did not do a typical install. I chose to do custom install. At the end of installation, I did not choose to use the shortcut, quick link etc.
3. Now I have two FFs. One is the one I can start from my desktop shortcut and the other I can start from my d:\. But ideally I want to use two shortcuts say FF1.5 and FF1.0.
4. So I created the shortcut on desktop using RMC menu.
5. I created a new env. variable, moz_no_remote and set it to 1.
6. I executed FF1.5, it started with the default profile.
7. Same for FF1.0, now I was asked if I wanted to use the default profile, or create a new one or rename the exististing etc. etc. I chose to create a new profile for my FF1.0.
8. Prima!, I was using two versions for FF at the same time.
Have fun!


Note 1: In http://www.hiveminds.co.uk/node/3114, they mention to modify the shortcuts and append "-p default" and similar things after the path to the executable. I did that, but still had to create my profile manually. So I am going to to investigate if appending path is necessary and accrodingly will modify the post.
Note 2: These steps suited my particular environment. If you decide to follow them, kindly do so at your own judgement.
Note 3: You can get older versions of Firefox from
http://ftp.mozilla.org/pub/mozilla.org/firefox/