There isn't much out there in the way of PCI 802.11n products. TP-Link TL-WN851N, Atheros Based (2x2MIMO) or the TP-Link TL-WN781N, Atheros Based (1x2MIMO) should work, but I haven't personally tested. You can always check the Mikrotik Hardware Page http://wiki.mikrotik.com/wiki/Supported_Hardware A...