Question : Problem: Backing up Exchange - What services should I disable (OWA, SMTP) ?

We backup our SBS 2000 server / Exchange using Veritas Backup Exec (yes I know its old now!).
Currently we backup at around 11:00 pm, which takes around 3.5 hours to complete.
The server has a Sony AIT 1 tape drive (SCSI 160) and backup totals around 26 GB including Exchange emails and data.
The issue we have recently is that people who log on to the system remotely using Outlook Web Access appear to be doing so after 11:00 at night when the backup is running! This has caused some backups to fail due to changed emails in Exchange etc.

Should I be disabling OWA and maybe even SMTP to stop any changes to emails while backing up?
Currently we use a PRE/POST job in Backup Exec that stops the VSAPI virus scanning of Exchange (advised to by most Anti Virus companies).
I could incorporate many other jobs to stop services into this, but is this necessary? I know Veritas Backup Exec is supposed to do an "Online" backup of Exchange but is this really reliable considering the data is changing (new emails coming in, being sent out etc).

Can someone recommend what the best services are to stop whilst performing a backup of an SBS / Exchange server....
Also should we be looking at replacing the tape drive with either a new AIT 3 or Ultrium LTO drive? What would be the best to use nowadays?
We will look to be replacing the server soon, so I should imagine an External drive would be best which we could utilise also on the new machine.

Appreciate any comments.

Chris

Answer : Problem: Backing up Exchange - What services should I disable (OWA, SMTP) ?

Thanks so far.

I understand that Exmerge will do a "Brick Level" backup, but what difference is this to doing on with Backup Exec during the nightly backup?
Also, Exmerge is a manual process so I assume when you suggest this you mean writing a script that runs Exmerge on ALL users and then saves them into a specific folder that is automatically backed up with the usual data backup?

How much better would this be that what I am already doing?

To be honest I would rather have some more examples of what others do who use Backup Exec and attempt to use the standard individual mailbox backups, as wells as information store.
Currently I have written a script to disable OWA during the backup time, which prevents any users from access emails.
Also VSAPI is now disabled, so is this all correct?