When you say push is this a warranty replacement? If so you are getting a better CPU than you had. Dave's numbers are correct here is numbers on the L2 difference.
Do keep in mind that the 17% clock speed benefit in no way translates to 17% performance increase in games or really most applications but a few. 17% is right on the borderline of even being perceivable on those where it does translate. So short of a stopwatch you are close to not even being able to tell.
All that said of course the T9600 is better in all ways other than thermal output. I agree T9600 might not be an upgrade worth doing later depending on cost.
If you are buying now with your money not warranty I highly recommend going i7.