"you need permission to perform this action" copying a file

It's almost embarressing to ask this but I need help copying a file
from a network share to my Vista computer. For some reason I am
completely blocked when attempting this.

Here's the situation:

* 3 gb ISO on a networked-pc (running XP) file share with read
permissions. i can see the file in Windows Explorer after providing
network login credentials.
* when attempting to copy to any folder on my Vista Home computer
(tried desktop, c: root, and 'downloads') I am denied with a error:
"you need permission to perform this action"
* I've read various other posts on the matter which all point to
ownership issues. I have taken ownership over the local folder and it
makes no difference
* Initially I had ACL turned off but have since reactivated it to see
if that helped. It did not.
* I log in with a local user to Vista but use the same username (with
different password) when connecting to the network.

What the heck do I need to do to copy a file off the network??

Any help is mucho appreciated.

The problem was that the network permissions were set to 'list' but
not 'read'. Apparently, I was barking up the wrong tree with the
permissions on the Vista side. The new error dialog through me off.