Is there a Virus checker program that can run via a DVD or external to the hard drive? I would like to do a scan for any virus on the HD but do not want a resident one due to impeding speed of daily operation. The other alternative could be a check from within OS Lion utilities if there is something there?
As a rule, I do not open any unidentified attachment unless it's a friend and the file is not of a Macro nature.
Any suggestions would be appreciated.
I realize that by "virus" you mean malware in general. Thomas Reed, who is probably the most qualified helper here on ASC in this area is recommending VirusBarrier Express, which is free from the Mac App Store. In recent tests it came out rather well in detecting Mac malware. It only runs on demand scans, doesn't install any system modifications and won't permanently slow anything down. But you do have to have it on the drive to which you are booted, which would mean the internal drive.
For more see
But don't let any A-V lead you into becoming complacent about where you browse and what you download. No A-V will find something that is emerging or yet to be cataloged. And no A-V will catch everything.