How much RAM do you need?

Linux rocks until it OOMs.  Running out of memory is never fun.

How much space does the average apache process take?  Or java process? Or mysql process?  

Try these to find out:

for i in `pstree -paul|grep [h]ttpd | awk 'BEGIN {FS=","} {print $2}'`; do pmap -d $i 2>/dev/null | awk '/private/{print $4}' | cut -d'K' -f1; done | awk '{sum+=$1} END{print sum/NR/1024}'

for i in `pstree -paul|grep [j]ava | awk 'BEGIN {FS=","} {print $2}'`; do pmap -d $i 2>/dev/null | awk '/private/{print $4}' | cut -d'K' -f1; done | awk '{sum+=$1} END{print sum/NR/1024}'

for i in `pstree -paul|grep [m]ysql | awk 'BEGIN {FS=","} {print $2}'`; do pmap -d $i 2>/dev/null | awk '/private/{print $4}' | cut -d'K' -f1; done | awk '{sum+=$1} END{print sum/NR/1024}'