First Time Home Server Build

Hello,

I hope you can help me. This is a lot of questions to answer- so thanks in advance.

I am setting up a home server. I have a Dell Inspiron 4550, P4 w/ 512mb ram, with a clean install of XP Home on it.

I want to turn this computer into my home server that will server multiple purposes. I will be upgrading the ram and the hard disk once I have developed and got everything setup. I want to be able to set this up using free/open source whenever possible.

Currently, my network consists of cable modem into my Linksys WRT-54G wireless router with DD-WRT flashed onto it. I have two Vista machines (Laptop - Vista Enterprise; Desktop - Vista Premium). I also have a Playstation 3 connected wirelessly. Here I have broken down what I require for this server, and what I would also like if possible.

Required:
1. Automated backup of two Vista machines. I would like to be able to do this automaticcaly on a schedule that I set. What software will I need for this?
2. Act as a Media Server for my PS3.
3. Act as a movie ripping and encoding computer. What software would be best for taking DVDs and turning them into formats compatible with PS3?
4. Will need to remote desktop in on this machine pver my network since I will not have monitor for this server.
5. Able to access files remotely, say from when I am in school or something. Will need Dynamic DNS. Which service (free) is best?
6. Act as fileserver.

So with these following requirements- what would the best OS for this? Should I look at some Linux distribution? Which one?

Does anybody have any experience with something similar? What about guides on the internet? Is P4 going to be decent enough to function as requested?

Thanks again for all the help.