How to connect with at&t u-verse wireless from across house?

I've got a custom built PC I've had for a while now that has a wireless network adapter Rosewill N900PCE, but just moved to a place where the wireless refuses to be of any use and continues to frustrate me. Situation is:
- AT&T U-Verse (no choice there) tv/internet service
- My PC is completely across the house through many series of rooms, halls, and several, several walls.
- It rarely picks up on the wireless network we have, and if/when it does, it moves at download speeds of 10 kb/sec and lasts for maybe 0-5 minutes at a time (aka. hardly exists).
- Can't even load webpages with moving graphics. This PC is a GAMING MACHINE. Which I clearly haven't been able to do since moving here.

In any case, pardon my woes.

Question is: What's something I can do to get the network connection to connect and stay connected and to be of a decent speed from all the way in here without the use of spiraling an ethernet cord throughout the house? (Impossible feat.)
Is there better wireless adapter that would do magic? Or can someone please recommend something that'd more or less solve this issue? I was looking at something like NETGEAR AC1200 WiFi Range Extender, but would there be better?
PS. I am very limited as to where I can add/place things like this, since I live with family. In my room where my PC is would be best, but I know beggers can't be choosers. I'm a student so can't spend an arm and a leg either. I'm slow on knowledge with this type of hardware, hence why I'm here!

Thank you in advance, especially for undergoing my rambling.