today i went on a fansite of christina milian and all of a sudden my computer restarted by itself and when i came back on the computer it told me on my startbar that "my computer got infected and click here to install xp security center and remove it" ...i thought it was real so i clicked it and installed this xp security center then closed it when the scanner came up.... i can't get on any IE sites...nor can i download HiJackThis .... the only way i am writing this because i am on firefox mozilla and for now it's still workng... it has also completely changed the way my Control Panel is looking.... i am using XP service pack 1.

can anyone help me remove this virus please... i don't know what to do!!!

forgot to mention... i can download HiJackThis.. but it doesnt run or open!!!