Yes you can get married to a green card holder. His citizenship application is only going to expedite the processs of your application.
When you say you are non citizen, what is your status, did you enter the country legally with a visa?
If you entered the country with a visa and you marry the green card holder, the draw back is when your husband applies for you based on hisgreen card you would have to wait around three years before your visa becomes available to apply for your green card. However, if your husband obtains his citizenship while your application is pending, you canimmediatley request that the USCIS upgrad your application and file for your green card. Good luck.