I'm using exactly the same card model and it has had kernel support since 2.6.24, if I remember well. I'm completely sure it works on debian squeeze (6.0) because I've tested there and besides, it uses kernel 2.6.32 (indeed, it should work on debian lenny, since it uses the 2.6.26 kernel, if I'm not wrong).
BTW, if you're interested, this card uses the rt2500 chipset; the linux driver is developped by the
rt2x00 project.
Regards.