Marrying a US citizen won't do any good or bad for you. Normally, if a greendcard holder is married to a US, the GHolder is elligible fo apply for citizenship within three years. In your case, without any marriage to UC, you will be able to become a US citizen on your own. Therefore, unless you marrying out of love, marriage to US citizen is in vain as regards to deriving an immigration benefit....good luck....As far as switching from asylum to marriage based greencard, you first cancel your greencard. Once you cancel it, you must file a new greencard based on your marriage. It is possible that you may be deported in the time between when you cancel your greencard and before you apply the new one. This could be a day or two or a week you might be out of status. Once you file the paper work for the new greencard, your case won't go through the process as FBI and other securities will pay special attention to you because you abondaned a greencard and looking for another one. If everything works well, you will get your greencard in 2011. and then it is conditional. you will be at mercy of your USC who sponsered you. slave........................................................you will be better of staying in your current status...good luck