Questions about installing Leopard

I'm about to make the switch and install Leopard on me MacBook Pro. Now I still have a couple of concerns...

First of all:
I was told that I should make an "Archive and install" of Leopard because the upgrade was "buggy". Now someone sent me the link to apple's site explaining what this was but I'm still as lost as before (maybe more so now) to why I should do this. From what I read if I check a button, I can keep my home folder in leopard but the system of 10.4 will be kept somewhere else and applications will work but not all, some will bug out needing a re-install.

It all seems so complex, could someone please, very simply, explain to me how this will all work (ie. Where will all my files be? my home folder? my apps, the old system?)

And also once this is done can I trash the old system?


And Secondly
If I decide to do it the simple way and just upgrade Mac OS X what will happen?? what bugs are we talking about here?

Thanks in advance!

 

So basically I will have access to all my files that I currently have? and will they be in the same location (relative to what I will see)?

And what about my apps? I have a ton and I don't want to re-install it all!

And again, what can go wrong with the upgrade and what do you mean by "poking around"?? (sorry as my level says, I really am a newbie)