Vista - Sharing Vista File With XP Machine

I'm trying to send a backup of my Quicken file from my Windows XP machine to
my new Vista machine. I've created a folder in the Quicken program directory
on Vista called "BU from XP". Here's the path shown on Vista: Computer >OS
(C)> Program Files (x86) >Quicken >Current Qdata>BU from XP.

When I go to the XP machine and look at My Network Places, I find in the
Name column:
* BU from XP machine on Xps435 (the name of my Vista computer)
* Current Qdata files from XP machine on Xps435
* Quicken 2008 HB on Xps435
* Quicken Data Files on Xps435
* Quicken on Xps435

When I double click any of the above I get ( for eaxample, the first one):
\\XPS435\BU from XP machine is not accessible. You might not have
permission to use this network resource. Contact the admin etc.

The network path was not found.

I can understand why it can't find the path; it's not the path. I would
think that what should appear in the My Network Places tree is a path like
the one in my first paragraph. I shared the files on the Vista by right
clicking an making my selection. I'm lost!