I would like to extend my wireless network using an AP900 talking to my 2860Vn+

I have users who wonder around the office with Samsung phones and iPads and I would like them to have seamless connectivity when switching from the 2860 to the AP900. Several users use VoIP services like Skype. In my previous setup this would happen...

1) User connects to wireless AP1 and make a call
2) User would then wonder around and fall out of range of AP1
3) The device would then pick up AP2 and connect
4) User would have to redial to continue call

I understand my new 2860Vn+ and AP900 allow "fast hand off" by reducing the hand-off delay in WLANs during transitions between access points??

Does anyone know how can I configure this feature?

I understand my new 2860Vn+ and AP900 allow "fast hand off"

I think you need to use 802.1x

Great but I don't have a RADIUS server, what's the cheapest way of implementing one?

(assuming I don't have any spare kit to run say a linux on)

Forget that, I've just noticed the AP900 has got a built in RADIUS Server...off to try it.