If you want to revert back to build 7048 without having to do a fresh install and re-install all your programs you CAN actually do an "Update" from Windows 7 7057 to 7048.
You'll just get a Warning that the version is older than your current and that a device or two might not work --mine indicated the Motorola sm56 fax modem -- but I've got the driver
for that anyway if I want to use it.
This leads creedence to the fact tha 7057 was "an Interim" build never intended for serious development use whereas build 7048 was actually part of the "True" development cycle.
Maybe my English might be mis-understood here -- I am NOT implying that build 7057 is a FAKE but just that it is a "testing" type build designed to check out certain parts of the process -- for example a lot of people experience longer install times before the Language menu comes up (perversly the better your gear the longer it takes to "start").
My advice would be that if you haven't installed 7057 don't bother --stay with 7048 until the next decent "leaked build" or the official RC1.
At least you won't have to look at the HIDEOUS logon screen.