Fire up Software Update or head on over to QuickTime's official download page to grab the 7.4 update. While it fixes:

• CVE-2008-0031: A maliciously crafted Sorensen 3 movie file may lead to arbitrary code execution
• CVE-2008-0032: A maliciously crafted movie file may lead to arbitrary code execution during the handling of Macintosh resource records
• CVE-2008-0033: A maliciously crafted movie file may lead to arbitrary code execution during parsing of Image Descriptor atoms
• CVE-2008-0036: A maliciously crafted PICT image may lead to arbitrary code execution

it does *not* fix the most recent QuickTime flaw, however, so continue to watch which sites you visit. Remember what your mother taught you: don't accept streaming media from strangers!