Welcome and thank you for giving me the opportunity to assist you with your tax question.
Your question merits a lot of explanation. The best information I have found that is contained in one place which is very easy to understand is at http://www.section179.org/
Please follow along in the text and click on the questions at the bottom. You will start with Section 179 which has a limit of $500,000 for 2012 (retroactive).
After reviewing this information, if you have any other questions, please let me know. I will be available tomorrow and will be happy to further assist you.