Hello Dhiraj,
Look what difference it makes when you put across the full & complete facts while requesting for advice/suggestions?
You have a very valid point & case to quit. But I still would say this: you could have handled it better--since it's been your exp that they did take advantage of you, you should have--sort of--expected their response if you resign. And based on what you mentioned, your boss WILL NOT give his OK for the Notice period pay-back.
Since you worked in this Company for 2 yrs--which experience isn't something one can ignore--I think you have 2 options:
1] Try to talk to the new company if they can wait for 2 months. If not, let go of it. But keep looking for new openings where the Joining time can be 4-6 weeks. All the while let the clock keep ticking here--meaning don't take your resignation back. To an extent, this will need some self-confidence on your calibre & faith in HIM too :-), that you will definitely get another job. Given the present post-recession market scenario, it may not be difficult--but it also depends on your confidence level.
2] Use this to get a better deal [Salary-wise or designation-wise] with your present company. If it's an IT company, it may not be difficult. And use the extended stay to gain more exp & then make your move after a few months, with better planning. [I did this way back in 1985 when I was in a similar situation in my first job--hence I know this can work too :-)].
Rgds,
TS