I have finally go so fed up with the confusion relating to 'Log Drops' in virus levels that I have written a simple calculator to deal with it. The link below will download it, and you can save it anywhere on your PC, and make a short cut to it should you wish. Alternatively, use the 'Run' option to use it from the net. Feel free to distribute it to anyone who you think might benefit from it!
Hope it sorts out some of the confusion!