4WD is surely better though? I remember that episode of Top Gear where he was testing the X-type estate with 4WD and despite being on standard road tyres he was having no problems with traction.
Having said that, our Mercedes is so much better on the snow and ice than the IS200 - is that the weight making a difference? (it's also that the ESP is far more responsive than the TRC in the Lexus)
as far as i know most modern SUV's 4x4 are predominatley front wheel drive only kicking into 4x4 when they need to, which is an advantage in ice and snowy conditions, having the weight over the driving wheels