I have Windows XP also on my home computer, and I used www.ziphone.org. You save it to your computer, unzip, and a great screen comes up. You can unlock only (be able to use another carrier), jailbreak only (be able to put 3rd party apps like solitaire, etc. on your iphone) or do both. I only jailbroke and am still with AT&T, and it took one minute and everything (contacts, etc.) was still on the phone from before. It installed App Tapp Installer and from that, I was able to download games, a to-do list, a money program, and a program to change my icons/background. There are also many development tools, unix tools, etc. Zibri also installs a flaming Z on the phone which is just a link to his blog. You can get rid of that by pressing down on the icon until it wiggles and then pressing the little x. Anyway, now the warnings. Back up your phone first, just in case. I don’t think Ziphone will do anything other than make you restore if it doesn’t work, but I won’t guarantee that just because it worked great for me, it would work for anyone. It WILL void your apple warranty (but I do believe there are workarounds), and (as I would with any 3rd party programs – whether for iPhone, PocketPC, Palm or anything), it is totally at your OWN risk that you download and install anything. Many programs on the installer are awesome, but most are in beta. They may not be finished, and there are bugs. The only problem I ran into is that some great programs didn’t make the jump from 1.1.1/1.1.2 over to 1.1.3/1.1.4 very well and the developers are either working on it or waiting to see what they can use with the SDK – my summerboard locked up trying to use a theme and I had to restore and restart – but for me it was painless, just the time I had to do. I would suggest that you read any faq’s, and check out www.modmyifone.com for readers opinions on all the types of jailbreaking – you have to search through a bit, but a search on google should bring up many sites and I do believe modmyifone has links that are good. Again, proceed carefully, but I hope you have fun.