XP takes 13 min. to boot, then is ok.

I switched from McAfee to Norton. In the process I added 2G memory, total = 2.5G All is good except my XP pc boot time went from 2-3 minutes to 13 minutes. (??)

Norton is a well known resource hog, not to mention poor detection rates compared to alternate choices, including free ones, the simplest way to check this is to remove Norton, uninstall it, if your boot time returns to normal theres your confirmation of it being Norton behind this, if so you may wish to reevaluate your choices and use a better option.

Now you say you had McAfee prior, I guess you uninstalled the normal way ?
BOTH Norton AND McAfee are renowned for leaving entries in a persons system after uninstalling, this in turn often causes problems when installing a new anti virus, Kaspersky for example will refuse too install until you remove all remnants of these programs, so I strongly suggest using the Norton uninstaller to remove your Norton install, it is very easy to use and cleans out the leftovers, next get and run the McAfee uninstaller (MCPR.exe), or rather clean up utility, again this will remove all remnants of the software, at least with these tools run you remove possible issues with leftover entries etc.
If you wish a free anti virus the top 2 are Avast and Avir, most people use one of these, Avast requires registration, but this is free and easy to do, hope this helps.

You made two changes, so undo them one at a time. The easiest is to remove the additonal 2GB of ram and see what happens. If no change, put them back then follow 8210GUY's suggestions.

DO NOT spend any time online without AV protection though. In the interim, install Microsoft Security Essentials until you decide what you want to do.

MSE, Avast, Aviram Nod32 are all good (Nod32 is not free though).

Thank you 8210GUY & Ztruker Your suggestions are helpful, I'll follow through on them. "Norton" too, is "free" to Comcast subscribers. I liked the Norton suite format etc, but until I added memory my pc had become unuseable. Thank you.