mcofmc the way you use your two verses makes them contradict each other and it is because you are taking 1 cor 16: 2 out of context.
in 2 cor 9:7 paul is talking about being a cheerful giver and giving a predetermined gift of "worship" to God meaning you shouldnt be feeling guilty at the last second in church and plop in some money nor should you up your tithe if the pastor sits down next to you when the tithing plate is passed around.
yes there is a point that the 10% is mosaic law and Jesus came to Fulfill the law. 10% is a guideline because the Holy Spirit was not yet given to the people. now we have the Holy Spirit to let us know what it is God wants us to give. Most importantly is the heart.
1 cor 16:2 is a verse you need to read in context. i will try to keep this short.
1 Corinthians 16 (New King James Version)Collection for the Saints 1 Now concerning the collection for the saints, as I have given orders to the churches of Galatia, so you must do also: 2 On the first day of the week let each one of you lay something aside, storing up as he may prosper, that there be no collections when I come. 3 And when I come, whomever you approve by your letters I will send to bear your gift to Jerusalem. 4 But if it is fitting that I go also, they will go with me.Paul is writing a letter to the corinthian church telling them he is about to come to them. he wants them to set aside a collection of money for the saints back in Jerusalem. Paul tells them to set aside weekly an offering so that he doesnt have to waste time with collections when he arrives. the church of corinthians was a mess and Paul wasnt going to waste time with money when he should be teaching them. The church of corinthians was supposed to pre-determine a "carrier" who was trustworthy to carry the gift of money back to jerusalem to the saints. if there was any question of the integrity of the carrier then Paul would go with him.
I hope this clears some things up. | 
Tithe
