take out 64 megs from your system and xp would still run. microsoft does not say that the system would boot up in 20 seconds if you run it on 64 megs. running and working in optimal condition... two very different things.
if you still want to use xp .. disable all eye candy themes and all extra services ( http://www.codecavalier.com/blackviper/WinXP/servicecfg.htm ) . Your pc is just fine to run winxp with some tweaking . I run it on p3 600 mhz with 192 ram and startup time is arount 50 sec to 1 min and dont expect games to run at full speeds