That's funny. I saw the very same question a couple of days ago in one of the HT forums.
Answer is no. You need a HiScan Sony for this.
The xbr400 replaced the xbr250 and was the first Sony direct view CRT set to have this capability. It was then replaced by the xbr450 which introduced 2:3 pulldown into the mix.
Basically if you see 1080i in any of the Sony specs then that TV will do 480p also.