Hi ronin4,
You might be able to set up your AV program to automatically scan new files after they've downloaded, have a look through the program's options. I open my shared folder outside of LW & scan new files manually.

If you're happy with your current security, then you don't necessarily have to go & get something new. Which AV are you using? Some AV programs won't run side-by-side with others, you'd have to check that out.