DWA-125 works but loses signal

[Hash0]

Hi, this is my first post, well the fact is that I connect to my neighbor WiFi since few months. I connecto to the WEP 40 bits AP, it shows 70% signal strength but then it starts to range to 30%, 50% after a few seconds since connection till it loses the AP, I bought the WiFi USB from an Ebay seller, the thing looks kinda legit but the led is GREEN instead of the characteristic orange blinking led, I have Linux Mint 10.... when I check the wifi status with Iwconfig command, shows this.

NOT connected to any AP:

wlan0 Ralink STA ESSID:"" Nickname:"RT2870STA"
Mode:Auto Frequency=2.412 GHz Access Point: Not-Associated
Bit Rate:1 Mb/s
RTS thr:off Fragment thr:off
Link Quality=10/100 Signal level:0 dBm Noise level:-115 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

I'm thinking that I have been scammed but I NEED to be sure that's not some driver issue!, thank you.