After unsuccessfully trying two other ways of updating WordPress' absolute image links in my moderately large migrated site, I used this plugin successfully. ( WP Version 3.1 )
No need to sweat the exact form of an SQL Query or use phpADMIN, if you know that 'post_content' is the location where your image media links need to be changed ( and it is ) then this plugin will correct your problem.
Kudos to the developer for (actually and for real!) making this part of moving a site quick and easy.
Perhaps a more comprehensive solution to moving WordPress sites is coming from this developer? I would pay a reasonable amount for such a product.