Essentially yes. Here's how it works:

http://www.f-secure.com/weblog/archives/00002053.html
http://www.pcworld.com/businesscente...ssentials.html
http://blogs.technet.com/b/mmpc/arch...ake-innit.aspx

There are some good online sites which you can use to check if a site is legitimate or infected:

http://www.virustotal.com/ - Online virus scanner/site checker
http://urlquery.net/ - Site Scanner
http://www.unmaskparasites.com/ - Site Scanner
http://zulu.zscaler.com/ - Site scanner/inspector
http://www.avgthreatlabs.com/sitereports/ - Site scanner (part of AVG)