Ok, I'm stumped on something that really shouldn't be this hard.  I've
created some cool code to transform a dataset via XSLT into SpreadsheetML
(XML for Excel) and I'm storing the physical file on a file server.  Now... I
currently provide a hyperlink to view/save the file, but this won't work
outside the network.  So, I've been working on making this
hyperlink/linkbutton/button/whatever stream the file back to the user.  How
in the name of Zeus's butthole do I do this?

So, in simpler terms; how do I take a physical file and stream the sucker
back?  Ideally, I'd like this to work just like it does now with the physical
link to the file.  Click the link, it prompts you to save/open/cancel.  
Clicking Open pops up Excel and looky-looky, you see the file.

Heeeeeeeellllllllpppp.  AAaaaaaaaaaaaaaarrrrggggghhhh.