ok, after you upgraded the ext2 to ext3, then went to ms/usb toggle, exactly what file/s did you put on the card?
im just trying to get a better understanding of what you meant by, you already had the rom on the phone?? did you try partitioning your card with the rom on the phone and then rebooted?
it seems like you partitioned your card, then placed the contents of your sd card that you had copied to your computer, back on to the sd card and rebooted, in which case its not gonna work....you have to reflash the rom...the only reason your copying the sd card is if you got all your backups from like titanium backup or sms backup or nandroids or pics, movies, music....etc...and you want all that stuff back after you partition....