Hi Sudhir:
I was in the same case as you, but for a Dell server:
Running RH7.3 and needed RH Enterprise.
So I did the upgrade with a spare server, and everything was fine:
- Partitions were untouched. (even when they are mounted on hardware RAID).
- Users on the 7.3 system were conveniently mantained with their profile.
I must say I made the upgrade to Enterprise 3.0, not AS2.1
And I must also say that it was NOT RedHat enterprise but White Box Linux:
If you wanna stay legal and need no support from RedHAt, go for it, as it is an exact clone.
http://whiteboxlinux.org/