Your density will vary depending on what those websites will be used
for, i.e. if they're all simple html sites then you can achieve high
density, if they're all asp.net driven sites, then your density could
be lower. also, how you organize them can play a role in density, i.e.
will you be nesting them all in one application pool or will you be
assigning an individual application pool to each virtual. In that
case, memory willl become a factor in your planning. let me know if
you have any other questions.