>>17258746MSE and Nod32 are both good Windows antivirius programs. ClamAV is fine too, you can get a Windows version here:
http://www.clamwin.com/On Ubuntu, do "sudo aptitude install clamtk". clamtk includes both ClamAV command line and with a GUI. If you want it to run as a daemon, start the "clamd" service.
Though you shouldn't really need antivirus on a GNU/Linux distribution. Maybe to scan your Windows drive.