IE / Excel / XLA Help needed

OK, here is the scenario. An XLS file I created uses a third party Excel Addin file (XLA) and that all works great. Now I put this xls file into a virtual directory on IIS and try to open it. The problem is that IE launches Excel files in place so references everything via HTTP and obviously cannot find the xla which is located in c:\Program Files\Applicationname ... on the client machine.

It does work in Netscape because Netscape seems to download the xls first into a temp dir and then launch it.
Now to my question, how can I force IE to download and then launch an xls file; that is possible without getting the save dialog. The portal where the xls is inserted uses javascript to launch the file so I cannot rightclick and save as.
Also, a asp solution would nto really work for me so if someone knows of an app that does that!

Any suggestion is more then appreciated.


Edited by michael

Yeah, I was burning yesterday almost lost one of our biggest customers over that. Anyway. I figured a somewhat weird solution is to save the xls having not the worksheet that is using the xla as active. So using an either empty or calculated worksheet remedies the problem. Thanks for at least replying though