Vista giving service pack problem.

I had recently tried to install vista sp1 over vista bussiness edition.first it installed for 30 mins then the system restarted and instead of the login screen there was a dialouge that the computer is installing updates.i waited and after 1 hour it restarted and again instead of the login screen there was a notice that the computer is installing the service pack stage 1 of 3 then the it completed 98 % and then it displayed that the service pack could not be installed.i want to play gta 4 and thus was installing sp1 on my vista.please help.
thank you