Hey guys, I have owned three iMacs. The old one had Leopard, backed it up, then ended up buying a 24". Restored from time machine, backed that up regularly, upgraded to Snow Leopard somewhere in there. Just sold the 24", got a 27" core i5. Restored from Time Machine, backed up regularly. So...3 computers, two operating systems and not one clean install. I don't necessarily notice that my computer lags, but it seems as though people are always recommending clean installs and I want to get the most out of my core i5. Should i do it and migrate all settings and files after installing applications?