See if all of the fans on the case are installed and working, it might be worth buying some fans for any empty fan slots? Also if you can try and use water cooling, other than that there is not much you can do :P well there probably is but I don't know what they are because I'm a noob
I currently have in my laptop a single 100 MB/s networking card (it's also a bad laptop) but for christmas I'm planning to upgrade to a desktop gaming PC which I will build my self, but I was wondering as my internet is really bad (we're promised 2 MB/s but on speedtest.net I rarely go above...