We still believe that 1840 is the RTM build for Service Pack 1. The Windows Automated Installation Kit (WAIK) was updated recently and refers to this build number as the RTM build that was released to manufacturers on Monday.
Shortly after we put the files up for download, our server was slammed with hundreds of thousands of download requests and crashed last night, even after we made some changes. We had no choice but to pull the files temporarily, until we can get them back up on a seperate mirror, if that is even possible.
I will let you know what we can do about getting the files back online. Since SP1 is a free update that is going to be available to all licensed Windows Vista customers in March, I don't think that theres any issues with hosting these files. They are digitally signed by Microsoft. If we receive any request not to distribute the files from them we will not do so. But we are still looking in to bringing them back online.