Compatible CPU's for my Dell Studio 1535

Hi, i first bought my dell studio 1535 about 4 years ago. I was thinking of upgrading the the CPU unit and RAM to increase performance. However im not sure what CPU units are compatible. My current CPU is INTEL CORE 2 DUO CPU T5750 2.00GHz.
e.g. would a i5 intel processor fit etc?
If anyone has any suggestions/recommendations they would be gladly accepted.
ACawley