you have to buy it. The free one is the 32 bit version. And most likely it will recognize enough of your RAM to have a good performance for your needs.
Kees
so i recently got a new laptop, and it comes with a free win 7 upgrade. currently i am running vista home premium 32 bit and got it with 4 gigs of ram. i am a light gamer. the upgrade will give me win 7 home premium 32. i am planning to get the upgrade and want to know if it is possible to get the upgrade to 64 bit for less money? also is it worth it on my system? because i dont know if 32 bit will recognize all my ram.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic