Both will do OK with what you plan: basic web browsing, MS Office programs and managing pictures.
The i3-370M has a nice boost in overall performance.
What is the price difference in the laptops you're looking at? Got make and models for us to compare?Intel Core i3-370M 2.4Ghz CPU review
PCMark Vantage score: 5129 Intel Pentium T4500 2.3Ghz CPU review
PCMark Vantage score: 3694