Complex home network challenge (help please)

[Corn_Fest]

Here's the idea:
The Desktop and Laptop (which are both running Vista) will both have 3 user accounts: user 1, 2, and 3. When User 1 is logged on to either computer, he should see his own documents. If he makes a change to a file on the Desktop, that file should change on the Laptop too. Same with users 2 and 3.

Photos and Videos should be public and the same on any user on any computer. Also, My Photos, My Videos, etc. should redirect to these public folders.

The same iTunes library should be streamed to both the Laptop and Desktop, and if a song is bought on the Laptop, that song should appear on the Desktop and vice versa. Also, every now and then, the entire iTunes library should be run through drm-stripping software (if you have another suggestion, please tell me) and streamed to the PS3 (has wifi) using DLNA-compatible software, along with the public photo and video library. Then the non-drm'ed iTunes music, the photos and the videos should then also be accessable from the Wii and PSP's internet browsers through a website or something.

Also, all photos, videos, music, and documents should be backed up on an external drive connected to the desktop.
http://img170.imageshack.us/img170/9361/networkzf5.png
Here's the equipment:
(1) wireless router with 4 LAN ports
(2) some ethernet cables
(3) roughly $100

less $ = better.

Can you do it? If so you will get this cute little gif for your sig (http://img175.imageshack.us/img175/3047/ilovenetworkskk0.png) and a +.

[The Grim Reaper]

The user 1 2 and 3 thing sounds like you'll either need a windows server if you want it 'easy', Or your going to have to use TweakUI to change the location of my documents etc to a network share.
http://www.microsoft.com/windowsxp/downloads/powertoys/xppowertoys.mspx

Where will it be stored, a main server?, or is this going to be copy/sync thing? Synctoy is a great tool for this (i use it for backup to an external HD), but theres no automated sync built in (yet). Look for other similar sync/backup tools, rsync is good also, but its unix based.
http://en.wikipedia.org/wiki/File_synchronization#Programs

Looks like you'll need a media server of sorts with a web GUI to get media streaming, it'll have to have a flash 7 compatible player to work with the Wii's web browser. Maybe Mediaportal and MythTV have some kind of similar capability?

VLC Player has a web GUI with streaming also, but its not really a permanent streaming solution.

Also, please paragraph your post and I hope this helps.

[Corn_Fest]

I'm trying to stay away from servers, I'd like to accomplish this with software if possible. I'll look into Synctoy and stuff, thanks a lot! :)