Thanks a bunch to both.

I followed this tutorial and it worked - http://talk.maemo.org/showpost.php?p=891136&postcount=1

But one thing what i have noticed is that, if i try to install any apps or games from application manager, then on first try the apps and games are installing fine, but later on without a reboot, if i try to install any other apps or games again from application manager, then it gives me error - Operation Failed? Is this normal, cause previously i was not getting any error installing different apps and games from application manager simultaneously without any reboot. Also, it seems app manager is taking a lot of time calculating apps or games while installation?

Also, is it ok to install an android 2.2 or any other OS that supports dual booting in n900 in an internal memory or sd card? I was going to try it and why not.