The 2 standards work on different frequencies (11.b = 2.4GHz and 11.a = 5GHz) so they are incompatible. Having said that, the 1200 series AP is a moduler access point, and can be fitted with both an 802.11b radio in the back of it, plus an 802.11a radio can slot into the bottom of it. So if you have the 802.11b module fitted, the 350 series (And other 802.11b) cards will work.