Hi all, i have succesfully got the ralink card recognized in osx 10.5.2
However, osx offers the new connection as a regular enX device (being en1(en0 occupied by Lan)
I used the drivers wich are downloadable from the ralink site

What am i doing wrong, or cant i use airport with the ralink2500 ?

Nothing wrong, this is how it works.

Only Broadcom and Atheros chipset based cards are recognized as Airports, other wireless card are detected as "ethernet" ports.