Best Wireless Card for Desktop

My computer is not consistent at all with it's wireless speed currently i have a wireless n router running at 300mpbs but it is quite old, i was wondering what was a good wireless card to upgrade my desktop to. I built my own desktop so i'm installing a pcie card won't be too much of a problem, money isn't a concern at this moment. i want something with relatively low ping speeds as well as something that can take advantage of my bandwidth so i'm able to stream hd video

At the moment i have a cable modem hooked up to my router

A second question is a good router to upgrade to? i have a fairly old netgear router (2-3 years) and it keeps dropping the connection so i'll lose the connection on my laptop and on my desktop and i'll have to restart the router, it's annoying. i was wondering if the newer routers don't have that problem at all or if they do, dropped signals happen less frequently. once again money isn't too much of a problem

thanks