Old infected computer able to be reborn?

-we have an old 2006 HP that was infected probably last year, and has been unplugged and in my room. today I decided to hook it back up and see what was all going on. the only thing that I can verify I saw was a desktop blocker. the internet connection wouldn't work,and I couldn't change any preferences. is there anything I can do to wipe the drive,and then be able to use it after? I'm sorta good with computers,but not the programming. I just want *everything* off that won't affect the computers ability to code or go online. is that a really complicated process that would need an actual technician,or could I possibly do it?Please visit this link http://www.dban.org/ it will show you exactly what you are looking for.



EDIT- You dont need internet connection. You go on someone elses computer, download this program, and put it on a CD, then follow the instructions on the website. You will be happy with the results trust me.
can you boot in safe mode? try it from there. You will need to run an antivirus program from safe mode.



When you power up the PC, hold down the F8 Key, until you see the option to open in safe mode with networking. Remember, only the keyboard will work when make the selection to open in safe mode. use up/ down arrows to highlight this option and the hit enter key.
Put your windows CD in, boot from it, reinstall windows.
check for any ancient restore points and try one.



good luck.