Live Update Repeating

The last few days I have noticed what seems to be a problem with downloading virus updates.  I click -update everything now - the download runs and 57.8 mb are downloaded and installed.  I checked the detail on the updates and they are the same files everyday.  My mac software is 10.5.8 leopard,  that  was updated from an early version of tiger 10.4.  I do not have the hardware which made mac compatible with microsoft programs found in later versions of tiger and leopard.