Yes, i forgot to mention about installing the official developer USB controller for SL (iousbfamily378.4.3_log.dmg) that came with the USB prober tool that helped me to verify that my wifi dongle was correctly connected & detected.

UPDATE: after I restarted my machine, the connection was lost (wireless is fully connected yet there was no internet, ie; couldn't load any pages). so after looking for solutions from other the internet from my (lucky i haven't erased my Leopard partition yet!) i found a solution that worked for me:

1. Downgrade my wifi connection security from WPA2 to WPA
2. Delete my dongle service in the Network preferences
3. Delete "com.apple.network.identification.plist, NetworkInterfaces.plist and preferences.plist" from /Library/Preferences/SystemConfiguration/
4. Add new location in the Network preferences (it detected my dongle again)
5. Restart and boot with -F

Since then, I didn't face any more problem connecting & loading pages after shutdowns & restarts so far. Hope these would help.