more wireless range needed advice

[winty03]

Looking for some wireless boost. What I am trying to do is get wireless to my MBP in an office a bit out of range of my TC. I attached a rough picture of the layout I am trying to set up in. The blue box is my TC that is located high in an upstairs bedroom and the red circle is where I would have my MBP. The black boxes represent wood/sheetrock walls of 3 other apts I am attempting to "go through" to get to the office. The curved line that runs between the 2 sets of boxes is approximately where I loose signal. Measurement wise its around 50ft from where I loose connection to the MBP (plus one wood/sheetrock wall.) Do you believe if I get an external wireless card (been looking at the Alfa 500mW USB Wireless B/G) and connect it to my MBP I would be able to get internet or would I still not connect being the TC signal is short? Looking for some advise. Thanks