socket 478/479 and ram upgrade problems and questions

i recently got a dell latitude d620 as a gift. this has a T5500 cpu @1.66ghz 512 mb or ram, and a Mobile Intel(R) 945GM Express Chipset Family graphics acellerator. I know that this laptop is not for gaming, but i want to upgrade it to be able to play counter strike source and day of defeat source, maybe some other older games.

I build computers, but i honestly know nothing about laptops. i used cpuz to find out that i have a socket 479 m cpu, but the online manuel and dell website says that its a 478. Im looking to upgrade the cpu to another dual core at atleast 2, maybe 2.2ghz. so im asking if anyone knows of any processors that i can upgrade to.

I also need more ram but i cannot find the dimm type. cpuz says that i have a pc2-5300 333mhz stick of ddr2 ram, but i cannot find that on any online stores. if anyone has any ideas please post. thanks