Can i run 64 Bit On My Computer?

Ok well my processor is 64 bit capable, I checked that. But how can I tell if my hardware and other stuff is 64 bit capable. I have a Dell Inspiron 530s that came with Windows Vista Buisness 32 bit. The vista malfunctioned so now I have it on XP Pro SP3, And I am going to upgrade to Win 7 and I want to do 64-bit so it can handle my ram =]