Seeking ''advance' advices prior installation of NAVISS 2009

Will be installing NAVIS2009 sometime next week but want to have as many questions answered ahead of time as i can manage:

           I have Win XP, SP2, ''DIALUP'...Earthlink Server.

Do i want to use Earthlink's spam-control option for mail AND NAV's?  

Do i want to uninstall my current security suite BEFORE installing the C.D. to start the installation of NAV?

Do i want to use first the current security suite's own program's  'uninstaller' BEFORE going to control panel/add-remove of the program?

Do i want to do a Defrag/restart  ''AFTER' UNINSTALLING' my current program and again after i install NAV?

Will i be ''on line' anytime during the installation of NAV ;

I know i will have to be on line after the installation of NAV is complete  in order to do Updates to current ones available...will i be vulnerable to any viruses, etc. while the updating is ongoing (which will be a long time for me since i only have dial=up) ?

               If there is anything else i should know about the  preparation of my computer installation or anything else i would be very appreciative ....

                              Thanks in advance for any input !  so  - Edythe