Just moved, networking woes

I recently (arrived this week) moved out from Wisconsin to Los Angeles. When I arrived the house I'm staying in had god awful Internet, but we upgraded it to Time Warner "up to 15mbps" speed.

This works OKAY, but there are frequent slumps to 2 and below.

My PC is upstairs and connected wirelessly to this home network. Tonight I tried playing Mechwarrior with my unit and it crashed out on me before we could hardly get started. Lame.

I know a wired solution is preferable but that's not possible here, since the modem is downstairs and this isn't my house to be dragging huge wires everywhere. In Wisconsin I had a wireless connection too without these sorts of issues.

I purchased a wireless antenna from amazon (http://www.amazon.com/gp/product/B006JWMOOI/ref=oh_deta...) hoping that will help me out.

Anyone help me out or know about this stuff? I'm pretty good about the technical side of computing, but I'm very ignorant about networking seeing as I never had problems with Internet speed back home.