i was able to get 54mbps, but only with the 3 meter cable that cames with the antenna. later, i bought a 6 meter extension cable, just to place my mini in my table next my bed, didn't work, 9 meters, even with coaxial cable, is to long, the signal droped to 9mbps, too much loss for me.
so, the next thing i did was to buy a wi-fi bridge, and i found a Netgear WGE101 on ebay for 35$ shipped, good thing is that this dridge has the same sma connection, so my existing 9-dbi-antenna+3m-cable-sma-connector works perfect with it. before some IPs and gateway troubbles and 3 hours later i manage to get the connection as i wanted, now i can put the bridge near the window, and run a rj45 cable across my room to my mini (whit ZERO losses!), wich now is connected to a 19" lcd flat pannel and a usb mouse+keyboard combo. with the wifi card disabled it doesn't heat too much as it did before. think about 10 degrees cooler.
pd: anybody knows the benefits of connecting to 2 simultaneous internet connections? i can do that now