NEVER UNDER ANY CIRCUMSYANCES ALLOW ANYONE ELSE TO USE YOUR ADMINISTRATOR ACCOUNT.
If u ever wish to let someone else use your computer in the future, turn on the guest account under user accounts in control panel, and let them use that account. That account is strickley locked down and prevents anyone from installing/modifying anything. I would suggest posting in the malware removal forum, scince u r quite infected. Also, in the future, mention those types of details, especcialy when someone like your necies comes over and then after the computer was messed up.
It's not your fault, so don't beat yourself up. And dont get mad at the kids, as they probably didn't intentially mess up your computer.

(depending on there ages lol)
Here is where you can get assistance in the malware removal forum:
before you post read this:
http://forums.spybot.info/showthread.php?t=288
Here is the link to the malware removal forum:
http://forums.spybot.info/forumdisplay.php?f=22
Explain everything that u did, like u did here, and provide them a link to this thread if nessary. Explain everything in full detail.

best wishes, 129260.