I've just switched over from Vodafone to Orange (I have no loyalties where new devices are concerned).
Order process was a bit of a nightmare. Lots of postcodes have changed in the Cambridge (UK) area, so Orange didn't believe that my credit card was registered to my home address. This was I think due to their credit card fraud checking system being out of step with their bank details system.
So extended order process aside on Wednesday I'll get some Windows Mobile 6 goodness in my life with one of these -
http://shop.orange.co.uk/shop/show/handset/orange_spv_e650/detail/pay_monthly