it would help if you went into greater detail with what speed exactially you are getting, weather that is mb/s or kb/s. The computer's CPU should have nothing to do with your download speed, it might be that if your downloading something on the first computer, it is taking priority over most of the bandwidth connection leaving the other one with a very slow downloading rate. There are many different factors that you have to think about when it comes to downloading things off the internet.
Are both your computers laptops? or are they desktops just wired to a wireless router? Is it your own wireless signal that you are using? Just wondering why your ping is so high, it shouldnt reach more than 10ms using a newer wireless router using the 802.11n band.
As for your downloading speed problem, like i said it could be a number of things. Check your MAC tables in your router and see if there is anyone else using your wireless.