It's working for me but I got an error message, are you sure you've got the new repo:
repo.iwoowiz.com
What do you want from there? If it's spirit2pwn or jbme2pwn then you can use pwnagetool instead (or get a friends ipsw and use redsnow to put you phone in DFU mode for the restore).
UPDATE: no it didn't add the repo.
Last edited by eyeRobot; 11-03-2010 at 10:55 PM.
Reason: Automerged Doublepost
New pwnagetool doesn't require you to be previously jailbroken.
Send me a pm with your email address (remind me it's 3GS you need) and I'll send you a link to download a custom firmware I created for 4.1 with pwnagetool.
To use it with windows you need to download redsnow and use redsnow to put your phone in DFU mode (only) then simply hold shift and click restore (in itunes) browse to the custom firmware you downloaded and let itunes do it's thing. Once restored you can just install ultrasnow from cydia.