Max processor upgrde for Inspiron 1545-PP41L Core 2 Duo T6600 2.2ghz?

Hi all,

I'd like to upgrade this beautiful old classic, but there seems to be some discrepancy as to how far it can be pushed. I gather it's a Socket P? Some sources say it can go only to Core 2 Duo T9900 3.06ghz. Other websites say it can be upped to Core 2 Quad, or even Core 2 Extreme. Which is correct? Thanks!