Jeany,
I would make sure that it was running smooth first, then you can turn System Restore on and off to delete all of the restore points. Afterwards, I would manually create a restore point just in case you needed it later.
It would make it easier on you to repair user accounts by having two administrator accounts in case somthing happens to the other one.
It's best to leace UAC running as is for better security, but if the UAC prompts are driving you crazy, you can elevate the administrator accounts instead of turning off UAC. This will let all administrator accounts not be bugged by UAC with it still on and with Protected Mode still on in IE7. This tutorial will show you how to if you wanted to.
User Account Control (UAC) - Elevate Privilege Level
Hope this helps,
Shawn