Buy better router or better adapter?

[StormCloudSeven]

I know the very basics of home networking but I want to get some advise on whether or not buying a new router would help with the speed of my chromecast in the living room and another wireless computer in the house.

These are the speed tested with the main computer that is currently WIRED to the router:
http://www.speedtest.net/my-result/5791590705

And this is our router right now:
http://www.linksys.com/us/p/P-E800/

Another desktop using a wireless adapter gets about 16 Mbps down and is located about 15 feet away from the router and separated by 2-3 walls, it uses this adapter:
https://www.amazon.com/Linksys-AE1200-Wireless-N-USB-Adapter/dp/B0054YQOM0

Our 1st generation chromecast is actually less than 5 feet away from the router, but in between them is a wall and they are effectively in 2 different rooms, it seems to stream 720p fine but usually have hiccups when we try to stream at 1080p.

Because its about to be Black Friday I'm looking at routers such as this one:
http://www.newegg.com/Product/Product.aspx?Item=N82E16833320154&utm_medium=Email&utm_source=IGNEFL111116&cm_mmc=EMC-IGNEFL111116-_-EMC-111116-Index-_-WirelessRouters-_-33320154-S2A6C

But I'm wondering if our router is even the issue, again I'm not trying to boost the speed of the wired machine, but the 2 wireless ones in the house. We've bought a repeater before and it seems to have helped for a while but it just felt too inconsistent. My question is will getting a better router do the trick, or buy a better wireless adapter and maybe Chromecast 2nd gen?

 

[hang-the-9]

Your issue is the walls it seems. Try using 5 gz vs 2.4 ghz connection. Also a powerline adapter may work better than a repeater, those are not very good.