Wireless roaming

Hi!

I have a few access points set up, how do I get the compuetrs to roam
between them? The problem is that the computers doesn't always connect to
the nearest access point (or the on with the strongest signal), but
sometimes it connects to a access point with much weaker signal strength.
And when the signal strength is to low it doesn't work that well and
disconnects every now and then.

So how do i get the computers to roam/always connecting to the strongest
signal? And is there a way of determing which access point they are
connected to in winxp?

Btw I'm using WZC to conifure the wireless network on the computers.