i also don't get spyware/adware with my current browser which is mozilla firefox. if you want a higher degree of security then install a personal firewall on your PC. if you can't configure a firewall try to use a free virus protection software. You can use AVG by Grisoft its 100% free with auto update feature. go to this site to download it:

http://free.grisoft.com/freeweb.php/doc/2/