Interfacing Java, USB and wireless sensor network

Hello all,
I've spent the last week looking through posts and google docs and I've made a little progress but I'm still at a loss for some parts of my projects, and would be grateful for any information you can provide.

My goal is to create a home automation/sensor network with attiny's, sensors, relays, and 433Mhz transmitter/receiver kits. I believe I will be using VirtualWire for this, unless there are better recommendations out there.

I'm planning on cutting a protoboard to fit in a pci slot (not using the connections on it) and mounting the transmitter/receiver inside of a PC, which will be running a linux server distro with a Java VM (and html/php server for web access). The protoboard will have the transmitter and receiver mounted on it, connected through a modified usb and molex adapters. I plan on using a Java program with VirtualWire to send/receive data from the sensor network.

My question is, can the program directly send serial data through the USB data+(to transmitter) data-(to receiver) lines, or do I need to have something in between to handle the serial data?

Thank you for your time