Yeah i went for that in the end, can't really argue for under a tenner delivered. Doesn't seem to be many other PCIE cards about anyway.
I actually already have 2 WLAN PCI cards,`which whilst they can't fit in my PC due to no more PCI slots available, they helped me test the wireless capability of the O2 box II and coverage in my house, which was suprisingly good despite 8 other WLANs on discovery (though i went straight for manual channel selection).
The PCI cards are a Belkin and a D-Link. Both are old but the D-Link just won't get recognized by Windows 7 and D-Link stopped doing drivers for it at XP. The Belkin on the other hand was picked up by Vista and Windows 7 and was configured with WPA in seconds off the O2 box .Hoping the TP-Link is as easy, no reason why it shouldn't be.
This was with the standard stubby antennas though I actually have a higher gain Buffalo (brand)Antenna i used with the above cards years ago on standby just incase, but no extra co-axial atm.