I've discovered a great resource for transferring large files:
www.youSendIt.com. They allow files up to 100mb in size for free, and more if you open an account. Sending large files in an email is insane - the process is not designed for it. Any number of things can go wrong. You Send It handles the process smoothly and cleanly.
If you're in the business of sending large files, pay for an account and be happy about it. Nothing good is free. If it's free, there is a catch somewhere.