product key help i cant activate my key

hi i just bought windows vista for my pc and im having a hard time activating
my key for vista i have 28 days to activate it and i dont know what to do, i
was typing my key in the windows activation menu and im getting this error
saying this

The Following failure occurred while trying to use the poduct key

Code 0xC004F061

then it says

Description

The Software Licensing Service Determinded that ths specified product key
can only be used for upgrade, not for clean installation. what am i suppose
to do? anyways i might just bring my copy back and get windows xp again i
been having so many proublems with vista plz help me with my question

Thanks Robert