If you are going to market your business in Twitter, is it best to set up your account with a personal name or a business name? I've seen both methods used and would like to add this to my marketing efforts.

Business name works better for me. I have both & use personal name to connect with friends who might search for me on Twitter.
Having business name ensures that when people search for specific topics like " fat loss" or " internet marketing" your twitter name pops up & one is likely to get followers which is more niche targeted.