Windows Mobile 6.5 is decent, but none of that bloated stock stuff they load on the phones. The best WinMo experience is done with custom ROMs for sure. From the looks of the phones you mentioned you have Sprint or VZW and it doesnt look like they are getting their Win7 phones til next year
I was really looking forward to Win7 phones until I saw the phones ATT will be getting. Think I might pick up a used HD2, unlock it and see what XDA can do.