Hi, I just bought a new PC running on follow config.

2GB DDR2 RAM
Intel Core 2 QUAD 2.33Mhz process
640HDD
Vista Home Premium-64bit OS

I feel that it's kind of slow, and I like to know if I should upgrade the
RAM to 4GB.
Further, I still have Windows XP Home CD and I am contemplating if I should
change my OS to XP Home instead.

Can some of you experts please give some advise ?