Ive not upgraded to 3.1

However ive manage to get my iphone into a boot loop. I did an erase all media and settings, in reset, and it seems to have failed. Now the phone just cycles through a boot with the connect to itunes screen.

itunes sees my iphone okay, and says its in restore mode.

Ive tried for 3 days now to get an older version of the firmware on my 3GS with out any success.

Im on a mac, itunes 8.1 so I should be able to restore the older firmware ? or is apple stopping this somehow too ?

Any ideas how i can get my iphone back.