need advice on building a home media system

[Woomera]

i have a database of music, movies and photos. i want them to all be centralized for access from different devices.

my devices:

• -PC running Vista ultimate (audio output: analog/digital)
  
• -Macbook running Mac os 10.5.8
  
• -Playstation 3
  
• -Samsung DVD home cinema system HT-TX35 (input: analog/digital - output: HDMI))
  
• -Western Digital 500GT external drive
  
• -AOC 22" monitor (supports VGA/DVI/HDMI)
  

Current softwares installed:

-PC

• Itunes
  
• VLC
  
• TVersity
  
• Windows media player 11
  

-Mac

• Itunes
  
• VLC
  

max budget can be spent: 150$ for now

what im trying to accomplish is to have all my media files centralized for access from any pc/mac/ps3. sharing thwm as folders works for pc/mac but if a new laptop enters the network its not that friendly to gain access over them, and the downside is that PS3 cant access at all.

tried Tversity and PS3 media server but content management in both is very poor.

the setup im using right now is i have the samsun attached to PC with Optical cable and analog o macbook and listening to music and watching movies.have the itunes library shared so can be access by any other itunes and have some folders shared via TVersity.using built-in speaker in monitor and attached the HDMI from PS3 to monitor.

what i came across to be somewhat useful is to buy a NAS(network attached storage) like WD world edition which supports itunes but again the support for PS3 lacks.

for now i can only spent 150 bucks, anyone have any advice or suggestions to make this more efficient?

BTW while i can efford to buy hardware's i cant buy any software since i live in iran.