I use the (R52) 802.11a+b+g 65 mW Wireless miniPCI Card
and it work like a charm
i have it today on 150 customers CPE units.
I have tested the SENAO 100 mv card called ARIES2 and i working well but its more sensitive to noise compared to the R52 card.
This is from the Mikrotik site :
MikroTik presents our new wireless 802.11a+b+g miniPCI card for multibandhigh speed applications! It can work either on 2.312 - 2.497 or 4.920 - 6.100GHz range.