Vista - Vista & IIS v7.0

I'm having some troubles configuring IIS v7.0 with Vista.
I'm running in workgroup mode...
I have a web host, but want to be able to simply work on my web site
locally...

I've gone through the process of creating an ASP based web site on my local
machine, can get it to launch fine in my browser...

All features of the site seem to work fine locally except for one...
When I try to 'import products' from an excel spreadsheet into my access
database,
I for some reason am getting Internal 500 Server Errors.

I know this is an authentication error, but for the life of me, I can't seem
to find the section of the configuration that get me past this point.

I've tried to go as far as 'Take Ownership' of the directory...
Set the .Net Security to minimal... and back to Full Internal ...
I've set Rights & Permissions to both Read & Write, Scripts & Executables...

Any advice would be much appreciated... Thanks in advance for your time.