Marlene, have a look at these tutorials. They will assist you down the road should something like this happen again. This forum has excellent tutorials that can aid you in every aspect of PC computing.
Tutorials - Windows 7 Forums
Clean Install Windows 7
Optimize Windows 7
Windows Defender Offline
This one in particular would be good to look at. A system image can save you a lot of time & problems should something like this occur again:
Backup Complete Computer - Create an Image Backup
I've dealt with Alureon. It writes a hidden boot sector that boots first every time you turn on the PC. So, it's already running by the time you get Windows initialized. Removal is not impossible, but all in all, the best/safest way when you get any rootkit is a clean install.
@ kevin s - Even with a severe rootkit, a disk wipe & a reinstall of the OS would have fixed that. I would do some serious complaining to the the higher ups of the manufacturer of that PC.