Your question: Should I choose JPEG or Vector?

Answer:
JPEG is a commonly used method of compression for digital images. In addition to this, JPEG is often considered to be the preferred file format for many desktop publishing appliations. JPEG is the most common image format used for storing and transmitting digital images. A JPEG image will be composed off small dots called pixels. The more dots per square inch, the smoother the image.

Vector graphics are basically shaped with mathmatical equations and use points, lines, curves etc. to represent images instead of pixels. Vector based images can therefore be scaled indefinitely without degrading in quality or sharpness.

Many of our illustrations are supplied only in JPEG format, and have 'JPEG' displayed in the type description.
Vector illustrations are supplied as either .eps or .ai files. If you like an image, but decide not to choose the vector format, you can always purchase the same image as a JPEG, since we ask our Vector-suppliers to include an image in JPEG format as well.

Please note that while rescaling in Vector images does not lead to quality loss, whereas rezising in JPEG format might.
Also know that in order to edit an original vector file, you need vector editing software.