This tweak for windows xp which is stop un-needed service insted of using msconfig
to disable service's

remove un-needed programs+applications from startup then tweak xp services

here is a link for tweak win xp

Windows XP Super Tweaks

we'll see what's on this site
but to be honest i have made my own "modding"
of services and after startup my xp prof eats only 80-90MB
although i have 512MB

greetz