Well if it's an eMac or Mini...go with the eMac since you gain "only some performance" over the Mini due to the faster HDD and this will help if you get into video.
I also have an eMac as well as the iBook in my sig. and I'm happy with both Macs. Just try to max out the ram no matter which one you get, it will always help and enjoy
I also have an eMac as well as the iBook in my sig. and I'm happy with both Macs. Just try to max out the ram no matter which one you get, it will always help and enjoy