omg...64mb ram + xp is a nightmare.
even 128mb is a nightmare, that being said its probably worth it, u need every mb u can get. don't load any wallpapers, turn off all fancy features graphics in system properties performance settings optimize that thing, make it ugly, no themes, no wallpaper, no nothing!!
and yea old memory is more expensive, and no old laptops dont' take much ram for upgrades at all, they just won't recognize bigger sodimms.
another reason why laptops just are very poor value for money