I intend to buy a new laptop - primary use is MS Office, watching movies / live webstreams and browsing. However, I do use it for video editing occasionally using a software called "Pinnacle Studio MovieBox". This software has a reqmnt for "direct x 9 or 10 compatible graphics card with 128 MB"
Currently I have HP G42-478TX, which works great.
As I look to buy a new laptop, if I go for an i3/i5 intel core processor (windows 8/10) laptop with Integrated graphics card (NO dedicated graphics card), will it be sufficient to run the above software? Or will I need a dedicated NVIDIA type graphics card ?
If you'll be using that new laptop for the same purpose I would go for a laptop that has a dedicated graphics card as well. Most of the new laptops today sometimes has 2 graphics card a Onboard and a Dedicated graphics card which would help do the task a lot better. But here are some laptops that has good on board graphics card as well.
The Intel HD 4400 / HD 5500 graphic cores should be fine especially they are a lot more powerful than the Radeon HD 6370 in your current laptop. I generally recommend a Core i5 CPU since it has Turbo Boost which acts like an automatic overclock for higher clockspeed.
The above recommended HP laptop (1st link) should be fine for your needs.