Just delete the US copy and start again from your new Battlechest DVD's - will be a pain to update - but the Blizzard downloader should be quite fast as there are no patches out right now for loads of people to gobble up bandwidth!
I wouldn't worry about gear to much that early - if you were only level 8 on your US trial account you can probs get back to that in a couple of hours on new proper account, and you should get some drops and quest rewards that will improve you. You'll be skipping through levels so fast that any gear is superseeded quickly anyhow.
Main thing to grab from the guild bank is bags as they make things so much easier early on
My ingame name is Bubalus btw - I'll be online later so can help out if you need anything