Sorry to hear about your troubles Hamm. I noticed you left the guild and was wondering why.
Anyways, I firmly believe that the word "hacked" is wayyyy overused these days. Most likely the "hacker" tricked you (or your brother) into giving out the password. Ask yourself these questions:
1. Have you ever bought or tried to buy gold for real cash on a website?
2. Have you ever downloaded a cheat guide or bot for guild wars from a site?
3. Have you made any new friends recently on guild wars (Yes, besides us)? People that seem really really really nice and friendly and trustworthy that could possibly have asked for your password for some reason, like to give you some rare weapon or gold because "well gosh darn it, they're just really super nice but their trade window doesn't work for some reason"
4. Could you have picked up a keylogger from a phishing site.
5. Have you registered your e-mail that you use for Guild Wars with any fan forums using the same password you use for Guild Wars. (yes, besides this one)
6. Have you given out your e-mail to anyone ingame for any reason? Someone ask for the e-mail to send you some cool screenshots? To give you a nice guide? Invite for a forum page? etc?
7. Could your younger brother have done any of the above things? Hmmmm??? (I'm getting warmer, aren't I?)
8. What was your password? No you don't have to answer out loud. Was it pitifully easy to guess? One person in our alliance was recently hacked. Her password was "guildwars".
Is your password "Hamm"? One of your character names? Your real name? "guildwars"? "game"?
9. Have you done anything recently that might have made you a target? Here's what I mean by this: Have you recently bought an expensive item? Do you walk around in FoW armor? Have you posted stuff like "Wow!!! Look at my new ultra rare minipet!!" in town or on a fan forum.
10. Could your brother have done #9.
11. Ok, not to pick on your brother, but....Ok, well yeah I am picking on your brother. How old is he? A lot of 11 and 12 year olds play this game and they are the prime target for scammers. An 11 year old kid is pitifully easy to scam. A scammer befriends him and gives him free stuff and somehow tricks the password out of him.
Just some thoughts. I'm sorry this happened. Look on the bright side. You learned a lesson with your guild wars account, not your bank account.