I thought I'd try a different quote this time. 
Granted, some people don't consider this official, but for me anyway it clarifies the issue.
Andargor

FAQ said:Say an 11th-level wizard has an Intelligence of 15. Can the wizard prepare a teleport spell (5th-level spell) enhanced with the Silent Spell metamagic feat and thus use a 6th-level spell slot that the character (thanks to low Intelligence) could not use to prepare a 6th-level spell?
Using a metamagic feat makes the spell occupy a spell slot of higher level, but it does not actually change the spell’s level, except for Heighten Spell, which does increase the spell’s level. So long as the wizard in question has enough Intelligence to cast the spell at its actual level (15 for the 5th-level teleport spell) the character can cast the metamagic spell. Note that the character doesn’t have to use metamagic to use the 6th-level spell slot; the character can simply prepare any lower level spell in the slot.
Granted, some people don't consider this official, but for me anyway it clarifies the issue.
Andargor