Sims 3 help!?!?!?!I'm using a desktop and....?

To be honest readyboost is more of a marketing thing than anything else. I would recommend getting at least 2GB of RAM since it is so cheap right now. 4GB of RAM can be had for $40. Another possible problem could be your video card. If you don't know what it is it could be onboard video which may not be powerful enough.