good q. if you can, use the same thing on the server as you use on your desktop. i use 32 bit ubuntu (8.04). if it performs fine on your 2GB RAM thinkpad, it will probably do fine on an ec2 box, no? if the config works on my desktop, it will work on the server, etc. tremendous advantage in terms of sysadmin requirements in my book. your mileage may vary depending on how much you like os x :>)