The highest video resolution of the S26391-F7136-L7 is 1920 x 1080 pixels. That's over two times the video resolution of a 1280 x 720 pixels webcam, which is the most frequently found video resolution.
A 1920 x 1080 pixels maximum video resolution is in fact the best video resolution across all webcams of this age and type.
A 640 x 480 pixels maximum video resolution is the worst video resolution amongst comparable types of webcam.
Alternative webcams that have a video resolution of 1920 x 1080 pixels currently available that you might also want to consider include because of it's better review score, the C615 (£49.98), or the C910 both from Logitech or the Creative Labs Live! Cam Connect HD (£53.49).