I use Vista x64.
I also use NOD32 3.0
as it has the smallest footprint (system resource use), fastest, most accurate, and most thorough scanning and cleaning. It also provides antimalware/antispyware protection. Product Software updates are free upgrades. You can back up config setting if you tweak for maximum protection, and It has also consistently won more VB100 awards, and other Independent testing awards than any
other antimalware/antivirus vendor out there. 3.0 is also a native 64-bit program, as opposed to many that are 32-bit running in windows on windows emulation.
For those interested in antivirus security, or If you are just looking for a program that will actually protect your computer(s), you should check out this link.
Most antivirus/antimalware programs are tested periodically by independent (non-biased) security organizations to see how well they perform. testing on the Vista SP1 platform was performed a few months ago by Virus Bulletin who awards the VB100 Award to those antimalware vendors that meet their high standards: (1. It most not miss any "In the wild" malware, 2. It must not give "false Positives", 3. It must do all this in it's default configuration out of the box).
note-"In the wild" means malware currently circulating and infecting systems. "false Positives" is the detecting of malware, that is in effect not malware. http://www.vistax64.com/system-secur...es-vendor.html