Wont Let Me Create PassWord

i recently bought a compaq presario (1 gig(put 3 more in) dual core x
4200 ) and it refuses to let me make a password i disable UAC stil
nothin Cut Off My AV still nothin it refuses to let me make a passwor
another thing is that seeing as how i bought it from best buy everythin
says best buy instead of my acount name like if im playin a game o
download a document or installing something it says C:/Best buy it migh
just have to contact best buy about that but any suggestion for th
password thinks guys....

--
Rseniss