Please advice on mac os x lion installation

I am new to MAC especially when comes to upgrading to newer mac os.
I am trying to install mac os x lion I bought and downloaded from mac app store. Its in my mac right now. I do have the latest mac os x 10.6.8 ready to be upgraded.
I did read every single line of this tutorial and so far I believe I am understanding correctly:
http://macs.about.com/od/macoperatin...n-Your-Mac.htm
Anyway, my question is:
This tutorial says when installing mac os x lion as a clean install on a target drive, there should not be any os x system files.
What happens if I install mac os x lion at my primary start up drive, is it gonna delete all the software installed there before because thats something I can't afford to lose basically don't have time to reinstall everything right now.
Just so you know, the most important software I have installed on my mac right now is VMWare Fusion 4.1.3(I believe latest one) and it has windows running and installed all sorts of softwares took me couple days.
Besides that I have eclipse configured and other important softwares.

Please advice if I can upgrade to MAC OS X LION without losing any software I have installed in my current MAC OS X Leopard 10.6.8.

Greatly appreciated and thank you so much in advance.
Rabin

robgendreau said:

First, you need to make sure that the software you want to use can run on ML. If not, why upgrade? Check VMWare Fusion in particular.

Second, you should never upgrade unless you've backed up everything, or at the very least all your documents.

Third, there is no need to do a clean install in most cases. Apple does not even provide such an installation; it's a relic of the past. Essentially it means you erase and reformat your hard drive and reinstall or migrate or clone everything. If you don't understand what that involves, don't do it.

Fourth, the best method is to follow Apple's own advice and upgrade per their instructions. Normally ML will install over your existing software and data. Some may not work anymore, but if you've done your homework it won't be a surprise. The standard method of installation works great for most all of us.

Rob

Click to expand...

Thank you Rob for your advice.
I have one last question before I back up my entire data using superduper and start installing LION in my start up drive.
First of all yes I can upgrade to LION.
During upgrade to LION, does it give me an option whether to format the target drive or not i.e. just upgrade to LION without formatting target(start up) drive?

Thank you again!!!
Rabin