Oh, that's a good one. I feel your pain of getting data out of SAP products, it's becoming a bigger issue for me too.
On the face of it, I think if you can get away from Access you might find it works alot better - are you able to use something like Firebird or a similar DB that you don't necessarily have to install?
Are you using Ms Office suite 2010 or something older?
Tableau 7 will bring about better extract/source management - you can have the server do the extract update once and then all the workbooks that need it can get that extract. I can see that solving a lot of issues.