The issue with excel not closing correctly when accessed programmatically is one of the most common reasons that I have found that server admins don't want devers to utilise the runtime within a server environment.

Utilising the ACE driver via SSIS currently on Office 12, you need to run the packages in 32 bit mode on 64 bit servers. there is however as discussed previously the Office 14 64 ACE driver. - currently beta but it should be released soon.

The additional benefit on the ACE driver is that you are writing SQL code and as my example showed previously you can incorporate all the complexities that you want right down to joining you data queries from excel with tables from other sources at the same time.