Contact POI after accepting offer?

[tragicomix]

This story starts with me getting an accept at a certain school where I was really interested in working with Prof. X. As soon as I got the accept, I e-mailed Prof. X asking him if he'd be taking on students and whether he'd be willing to consider advising me. I didn't get a reply for two weeks. After this I sent him a reminder upon which he replied saying that he was happy to hear I was admitted, and he was anticipating taking on some students. However, he said he doesn't commit to advising any students before meeting them in person.

In the meantime I was contacted by Prof. Y who showed a lot of interested in advising me. Now, my preferences at this university are Prof. X, followed by Prof. Z followed by Prof. Y. I really like Prof. Z's work but I was missing some background. So, I contacted Prof. Z to know if that was gonna be a problem. He replied saying that it wasn't a problem at all.

Since it seemed like I had a shot at working with Prof. X, and if that didn't work out, I also had reasonable "backup plans" in Prof. Z and Prof. Y, and this is a really great university and they made me a fantastic funding offer, I accepted. Since Prof. Y had called me and answered a lot of general questions I had about the program, I let him know that I was accepting the offer. He replied saying he was really happy to hear this and now introduced a new actor, Prof. U to the e-mail thread!

So a quick summary of the situation is like this, ordered by my interest in these professors:

1. Prof. X - has told me he doesn't commit to anyone before meeting them.
2. Prof. Z - I don't have the perfect background for his work, but he seems positive.
3. Prof. Y - I'm somewhat interested in his work, but he seems really interested in me.
4. Prof. U - Not sure where he entered the picture from, because I don't really have the background for his work and am not that interested in it either.

My question is, should I now contact Prof. X and ask him how I should prepare for the start of grad school this Fall? I want to do this for two reasons - (1) to show that I'm really interested in working with him and (2) do whatever preparatory work he suggests so that I can maximize my chance of working with him. Is this a good idea or does it come off sounding desperate?

Any other suggestions on how I can maximize my chances of working with Prof. X or Prof. Z without getting into a situation where I commit to working with Prof. Z (thereby precluding any chance of working with Prof. X)?