Need an MS exchange archiving solution

We are backing up Exchange 2003 database and mailbox (plan to move to 2010 soon) with Symantec Netbackup 7.5 for many years. Since we get restore, search and hold request a lot. We are lately looking for an email archiving/vault solution to allow us to have a central place to hold a full copy of all emails. What is your recommdation for this propose.

We are considering about Symantec "Enterprise Vault" or  Dell "Quest recovery manager for Exchange".

Thanks in advance.