<p>The 450m is good enough if you don’t plan on running two different OS at the same time. The 520m helps with that and a bit extra but you probably won’t use it. </p>
<p>The difference in speed only helps if you’re using a program that uses one core. Which programs does that I have no idea.</p>
<p>When I purchased my laptop, I just went with the 450m.</p>