In this video from sjsharksiPodtouch we learn how to jailbreak your iPhone 3Gs with firmware 3.0 using a Windows machine. With your iPhone plugged it, download the PurpleRa1n file and click make it rain. Then your iPhone will enter into recovery mode. You'll see the PurpleRa1n logo on your iPhone and then it will reboot. Tap the Freeze app, and tap Install Cydia. Once finished, exit and then reboot your iPhone. Now Cydia is fully installed. You will get a message on your iPhone saying Reorganizing, will automatically close when done. Now you have Cydia on a jailbroken iPhone 3Gs!