I am so sorry that I could not response in time, Thanks to all who have replied.
I have read all replies.
What I meant by archiving is to move data not to another DB, but to a seperate storage.
I was reading how Oracle 10G can benefit partitioning and I read this article, Information lifecycle management, how the storage cost can be minimized by partitioning most of the historical data at low-end storage.
Plus some advantages about archiving (data if neccessary) by using XML.
As I said I have very little or no knowledge about these issue.
I am really thankfull to these sites and people like you who help people like me.

Thanks again,

Habeeb