Macbook Pro - Wifi failure / airport card not installed

Model - Macbook Pro, late 2008/2009

OS - OS X 10.6.8

I assume that my beloved mac will now be dying a death but I wanted to confirm this before throwing in the towel.

System was freezing during net browsing and then I was faced with 'airport card not installed' issue. After visiting the genius bar twice, I was advised that the problem was not fixable due to the mac being now classed as 'vintage' (over 5 years).

Was considering purchasing something like a D-link -131 adaptor ((http://www.dlink.com/uk/en/home-solutions/connect/adapters/dwa-131-wireless-n-na no-usb-adapter) to see if I could manually connect to local wifi signal (without airport card replacement).... but after browsing web for any alternative I decided to try an SMC reset and success; I was able to logon to wifi!!

Or so I thought...

Despite my mac now being able to detect the wifi signal, the web browser is active for 30 secs - 2 mins before system freezes and I have to reset mac manually. I have tried alternative web browsers (Mozilla, Chrome etc.) though the effect is the same and as mac can no longer update itself (due to outdated OS) it seems that it may be done for...

Please also note that this web browser freezing issue occurred even before the 'airport card not installed' issue happened...

Any thoughts or advice would be much appreciated. I fear that it may be time for another £1200 debt.