Hi there! My name is Ivan Versluis. I am a Dutch IT Professional working for Almatis as Global IT Engineering Manager. Go to http://connect.microsoft.com website and download the service pack. You should participate the “Windows Beta Programs”!
Download the SP1 version. I downloaded the x86 and it took me 20minutes with 2MB SDSL dsl line. Start the Windows6.0-KB936330-X86_wave0_SPInstaller.exe and allow the exe to run if UAC is enabled.
See my screenshots which I took during the installation. Maybe it makes sense to double check Google for VistaSP1 issues. I read couple of posts people have issues when Bitlocker was enabled and Vista was upgraded to SP1; after the uninstall the encrypted files were not accessible anymore. 
Screen clipping taken: 11/29/2007, 12:03 PM
Screen clipping taken: 11/29/2007, 12:03 PM
Screen clipping taken: 11/29/2007, 12:03 PM
Screen clipping taken: 11/29/2007, 12:17 PM
So I went back to my own notebook and rerun the SP1; I reinstalled this pc two weeks ago with brand new iso file I downloaded from connect website. The installation took more than 90minutes and then I killed the process; no error messages this this, but again no upgrade.
vistasp1help
follow the guide on this webpage for sp1
please note all previous sp1 installations MUST be deleted
this is what i used and its great
u.z
vistasp1help
http://www.ghacks.net/2007/12/06/download-windows-vista-sp1-rc1/
alan
Do i need to backup my file To install the update?