This is a topshell for windows vista sp1 x64
this is most likely going to be final build of sp1 since well there is no more watermark and in system properties just says sp1 now unless they change something before public release..
please backup your shell32.dll in C:\Windows\System32
this is the exact file i used to get my topshell as you can see in screenshot, im not responsible for your mistakes. i suggest you make a new system restore point just in case of anything