I'm shopping for a new laptop as a desktop replacement (since I'm going to be moving around a lot, there's no way I could take a desktop with me) and I'm kind of wondering, as someone who rarely plays PC games, is there really much point in paying extra for one with a good graphics card?

I'm a designer (sometimes) so I do use things like Photoshop which can be GPU accelerated, and it affects video playback too which I do quite a lot of, but since I couldn't give two shits if it runs Crysis 2 on high with a good framerate or whatever do I really need to concern myself with the graphics card all that much? The laptop I'm looking at has a GeForce 520M which seems pretty low-end, but would going for a better one noticeably enhance the stuff I'm intending to use it for?

You should be fine. Your graphics card will mostly be used for window compositing and perhaps drawing a few surfaces (e.g. in Photoshop and your Web browser), which it can more than handle.