additonal mailbox new email alert pop up message

Hi,

We have a customer running SBS 2008 Exchange SP1 with Office 2010 on client PC's.
I have a couple of questions if anyone can help and advise.

1 is there any way for when they have open an additional mailbox in their Outlook for it to display a new message preview in the corner for they way it does when an new email arrives in their default mailbox?

2. Second is it worth upgrading to Exchange SP2 on their SBS 2008 server?
Reason I ask is they have had a problem recently with a certain few emails not even arriving at the exchange server at all even when I go into message tracking exchange has no track to say the message has even arrived as was wondering if SP2 is worth putting on to improve reliability? does it really matter if their mx record is set to 50 instead of 10 as the priority as they only have the one a-record and mx record setup??

Or if anyone has any other views on this problem the email is getting to the users hotmail but not the exchange server but the majority of daily external email is arriving at the exchange fine so the customer is losing confidence in the way email is working with the Exchange server and worried what other email may not be arriving.

Would appreciate any thoughts on this.

Many Thanks in advance.