No, you have more chance of getting a hat you nubs, just less chance of getting the hat you want, assuming you want 1 hat.
If you wanted 1 of the old hats, and didn't want any of the new ones then you would have less chance of getting the hat you want. Now if you wanted 1 of the old hats and 2 of the new ones then you would have the same chance to get a hat you want etc... Now I could also say that the chance to get a hat you want has increased, since someone could have wanted 1 old hat and then like 8 of the new ones, so personally his chance is high. So it's very subjective.
EDIT: Aha, i found it:
Every 15,430 seconds (4 hours, 17 minutes, and 10 seconds) you have a 1.1905% chance to receive a hat. These are the exact values used and is not something that was determined by using data collected from idlers.
Data from the King of TF2 3rd party programming 'Drunken F00l', confirmed by valve.
Unless of course the chance to get a hat is worked out by having a base 0.44% chance of getting one, then it could work out like this:
(4x60)+17=257 minutes
257/45=~5.7 item rolls in that time
5.7/2=~2.85 successful item drops (each time it rolls you have a 50% chance of a drop)
2.85*0.44= 1.25%
So this could be possible since the 0.44% is probably inaccurate since it was collected on the idler when it was relatively new. I bte if someone searched on google we would get an answer.