This isn't really a direct answer to your question, but a suggestion to all
who read this. The way I set things up is to create a small primary
partition for Vista and another small primary partion for XP. I installed
each OS and apps for each OS in those partitions. Then I kept a third
partition for documents. I have no problem accessing documents on that third
partition from either OS. (Same is true for all the docs I have out on an
external hard drive).

Hello,

Here's the easiest way I've found to do this.

Sidenote: Opening an administrator instance of explorer does not work in
interim build 5456 due to a bug.

1) Open an "administrator" explorer
- Click start
- Type explorer
- right-click windows explorer
- click run-as administrator

Any file or folder you access from this instance of explorer will be
accessed as a full administrator, instead of just a normal user. This will
allow you to easily browse and modify the filesystem.

2) From the admin explorer, allow access to files created from Windows XP
- Browse to the folder you need access to
- Right-click it
- Click Properties
- Click security tab
- Click Edit
- Click Add
* If only your account needs acces, type your username
* If every account on vista needs access, type: Users
- Press enter
- Click the checkbox under Allow next to Full control
- Click OK
- Click OK

Repeat step 2 for all folders you need access to.

- JB