change "owner" name of computer

i just bought a machine from a friend of mine. i have yet to reformat it, he has some stuff on one of the hdds that he want to get later, plus i need to get a raid card. long story short, i dont remember when i format this thing if it will allow me to change the name. as it sits now, there are some folders named barry that i cant change and when i put avg in, it automatically shows up as registered to barry xxxxxxx and not me. its no huge deal if i can change it with a format, but until then, its really annoying me. tia.

You can go into Regedit click on Edit->Find and search for the old name. When found->edit and replace...I

thank you very much.