weak signal

I have had my computer for about a month now and before I would always get a connection between 75-86% and now it is in the "low signal" area sometimes below 50% this happened after moving my PC and then putting it back and reconnecting the antennae. here are my networks specs

Router:linksys wireless B broadband access point
network card: PCI, Hawking technology wireless g
both are backwords compatable, I have it set for B only and no encryption, the wirless PCI adaptor has an antennae that screws into the back, it has about a 3 ft long cord with a black pastic antenae about 4 inches tall, I have it sitting just in front of my tower about 4 ft off the ground. It is about 20ft from the router through 1 wall. I am thinking that maybe the antennae is crap and it isn't amking a good conenction to the card. at this signal my internet is usable but noticably slower, I am using comcast broadband, and another note, I got the card at frys, it was repackaged and teh cheapest one they had, like >$20

 

http://www.fab-corp.com Carries lots of antennas and such, great site.

 

It would be better to put the Antenna above the Tower free of any obstructions all around.

The best Method to Extend Wireless Coverage depends heavily on the Specific Envioroment.
Look at these pages they describe most of the options that are within the means of Entry Level users, and choose the one that fits you envioroment best.

Link to: Extending the Distance of Entry Level Wireless Network.

Link to: Wirelessly Bridging Home / SOHO Network.

Link to: Hi Gain Antenna for Entry Level Wireless.