My laptop has got a virus can any one help?

1st of all i was just transferring music from my computer to my i pod. then all of a sudden my laptop just went black and the wallpaper went and changed into saying ''following viruses were founded on your computer: Trojan horse p capture and etc. your private information will be potentially transferred to third parties'' and it recommended me to download a spy ware tool but i never downloaded the one they recommended me to instead i got AVG. Now avg is scanning through my laptop but some of the files that viruses when i want to remove it using AVG it says your computer may become stability or even force to crash now i don't want to take the risk. Would anyone recommend me to get another program? take the risk? please help me out as i just got this laptop last week oh and by the way everytime i try to open my task manager it will say disbaled by adminstrator buy im the only one das using the bloody laptop:s