does my pc spec compatible with vista 64bit?

The 965 chipset does very well with Vista 64 OS. My ASUS P5B Deluxe 965 has Vista 64 drivers available online on the MB Product page. Check your MB product page for any available Vista 64 drivers for things like sound drivers, etc. Load up the Vista 64 OS then any compatible Vista 64 MB drivers MSI may provide on the product webpage/downloads.

yep. You are all set. Install Vista 64 and download and install any Vista 64 drivers and utilities available on your MSI MB's product page.

Processors have been 64 bit capable since AMD 64 releases maybe 5 years ago. I always give the simple explanation when asked what's the difference between 32 and 64 bit processing. 32 bit processing is like data traveling through a swizzle stick. 64 bit processing is like an information highway with data thoroughfare as big as the straw you get with your average two ton slurpee at Cirkle K.

http://en.wikipedia.org/wiki/64-bit

Motherboards you buy today are Vista ready. Any chipset/utility drivers needed for Vista 64 are provided by the MB manufacturers. Old MB's and old hardware for that matter may have problems with available drivers for Vista 64. You have the 965 chipset. I found my ASUS 965 MB provides drivers to run Vista 64 with no problem. It's running fully well as my son's gamnig machine as we speak. If you have very old periphals like say your printer or your wireless adapter, these kinds of 'old' hardware do not have 64 bit drivers available. Running a 64 OS requires surrounding hardware (printer, wireless adapter, sound cards, other PCI cards, etc.) that have Vista 64 bit drivers available. If no drivers are available for say your printer for example, you will have to buy a new printer which have Vista 64 drivers available. Same for your old sound card or wireless network adapter.