Mac OS X 10.4: Remove Virex 7.5.x
The presence of Virex 7.5.x can cause a variety of issues under Mac OS X 10.4, including slow overall system performance, constant fan activity, and degraded performance in some applications.
Instructions for uninstalling Virex 7.5.x are contained in an Apple Knowledge Base document. However, these instructions require that the user obtain the original Virex 7.5.x installation disk image, which can be difficult to locate.
Another option is to use the command line uninstallation utility from Network Associates.
Resources

http://homepage.mac.com/sjonke/VirexUninstall.zip
Note that while the resulting file has an extension of .command, it is just a
text file and can be opened with Text Edit or another editor if you wish to
view it. To run it, just double-click the .command file.