Two options come to mind:
1. Use a network drive. You connect it to the router and it can be accessed from all PC's (with the right settings). Here's just one I found with google (it's even wireless), but there are much more. But I'm afraid it doesn't list ps3 as a compatible OS for the systems using it.
2. Use a full-blown fileserver. That's a separate computer in your home network. An example is Microsofts Windows Home server (, but you can use a Linux box also, in principle. Here again, I expect the ps3 to be the problem. You might need to configure your server as a web-server (as far as I know, the ps3 has Internet access).

Just 2 Windows PC's won't be a problem.