Hello novita77 - Welcome to the Sony Forums

Your friend is correct to say that a high speed SD card would be a good idea. There are a variety of manufacturers available and there are various grades of cards available. As an example, you have cards like this selection available on Amazon:

http://www.amazon.co.uk/s/ref=nb_sb_noss_1?url=search-alias%3Daps&field-keywords=sd+card&x=0&y=0

As you can see, there are higher speed cards available for around £10 and these will give you a far superior performance compared to your old Memory Stick Pro Duo. One other factor to bear in mind is that if you have the picture quality set to the highest level on the camera, this will lead to a longer time taken to write the image data to the memory card. Unless you intend to get large physical prints of images, having a medium image quality will probably be sufficient so I would advise you to experiment.

Thanks,

Simon