QUOTE(dziningspot @ May 7 2007, 04:08 AM)
I had observed from my own sites that I lost the positions of the mainly targetted KWs when I focussed more on Users such as on Titles, Meta descriptions, Content, Images etc., and also mojor site Archetecture is changed that affected my ranks on Google. Well, I am assuming that I need to wait for some more time to see the results as this happened just two weeks ago.
If this actually affected your rankings negatively, then you did it wrong.
Without knowing what you feel is better for users vs better for SE's, it's hard to say for sure, but I've yet to see a site where improved usability hurt rankings, especially when it comes to site architecture/internal links.
I have seen a LOT of sites where the owners think
they have great usability/content/design when they really don't... not saying that's the case with your site but it's a possibility.
Also remember that if you caused
rankings shifts with on-page changes, then uploading your old site should cause everything to return to the way it was. If that doesn't work, your changes weren't the cause of the shift.