O2's Xda range of Windows Mobile handhelds has something of an aura about it. The original <a href="http://reviews.zdnet.co.uk/hardware/handhelds/0,1000000735,10001359,00.htm">Xda</a> appeared back in 2002, kicking off a line of O2 devices that has proved both popular and enduring. As well as introducing new models into the range, O2 has consistently updated the original Xda form factor, the most recent incarnation being the <a href="http://reviews.zdnet.co.uk/hardware/handhelds/0,1000000735,39193995,00.htm">Xda IIi</a>. The <a href="http://businessshop.o2.co.uk/phone_detail.aspx?id=94&groupid=4">Xda Argon</a> is another update.