Formatting during Vista set-up

[j_to_da_t]

Whilst installing Vista HP 64-bit yesterday, there was an option to format my disc before putting the OS on it, but instead of it taking 10 mins or so as it does with XP, it took about 20 secs. When Vista loads up now, it seems to think there's more than one OS on the system, giving me an annoying screen every time, asking me which OS I'd like to load, even though there should only be one - the new one.
So what's going on here, and how can I stop that screen popping up?

 

[DanMc07]

just delete your old os
put the cd in
go in the the format options when the pc starts up
and delete your old os
(thats what you do in xp anyway)