I've been using LinkScanner Lite and McAfee Site Adviser on both Firefox and IE browsers. Overkill? No way. Each program serves the greater goal of alerting you to dangerous links but differ in their approaches.
As publisher Exploit Prevention Labs explains it, LinkScanner Lite and LinkScanner Pro scan individual pages in real time, knowing that malicious hackers can hop from site to site, temporarily infecting them, even if a site may be safe 99 percent of the time.
LinkScanner Lite has repeatedly flagged unsafe sites that Site Adviser has cleared, like Megaupload, which I just searched today to follow up on a user's tip. This isn't to discredit McAfee Site Adviser, which provides valuable information about dangerous links, downloads, and spam e-mails within a given site. I see the freeware versions of these programs as complementary rather than exclusive.
LinkScanner Pro (about $30) does even more than the free "lite" version to extend your firewall's capabilities for blocking drive-by downloads and scanning IM links for distributed malware.
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