I think the problem isn't so much XP Pro 64 as it is logon user rights. There are a couple of posts about this:

WWW Link
and
WWW Link (particularly reply #10)

Short answer: If you're logging in with a restricted/limited user, you can use the right-click "run as" option to start Object Dock, using your Admin login and password. One warning about this though - you'll be loading up the docks created and stored under your Admin user, not your current limited user. In other words, if you've created and saved themes under the limited user you won't see them while "running as" Admin, the themes are stored and accessed based on the user. Multiple limited users would be sharing docks and to some extent be tripping over each other.

If it all is really a deal-breaker for you and you don't want to wait for it to get fixed, you can ask Stardock for a refund. On a personal note though, those 2 functions are the least useful thing to me about the Plus version, I never even used them after playing with them for a little while, didn't even know for a long time that they weren't working under limited users. Everybody has a right to their own favorite feature though.