I'm new in Ubuntu and just downloaded Ubuntu Gnome 14.04 LTS.
The PC is working fine. The problem is that the internet is kinda slow.
It loads the pages but it takes forever. Seen an HD quality video on YouTube is impossible.
I've tried what it says here:
http://pkill-9.com/stabilizing-atheros-ar9485-ath9k-connection-linux-wheezy/
However, where it says to write

cd /etc/network # go to network interfaces

sudo cp interfaces interfaces.org # make a backup copy

sudo nano interfaces

I get:

# interfaces(5) file used by ifup(8) and ifdown(8)

auto lo

iface lo inet loopback

And in 'HOKEY POKEY PART 2!' my PC shows the same message as in the step 5.

If anyone knows how to solve this problem I would really appreciate.

After using iwlist scan, this is what it shows:

 Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (1) : CCMP Authentication Suites (1) : PSK 

PS: I have dual-boot with windows 8 x64 and the internet works perfectly.