Assembled pcs are better than branded one becuase they come in low price and they all are coming with genuine parts too.
you can save as much price on assembled pcs that u can give five years annual maintanace contract to anyone. only one thing u should remember that harddisk should be of a renowned company like samsung or lg. I have got five branded pcs and they are not giving me trouble at all. u can learn hardware course ranges from 1500 to 2000 and u can assemble ur own pcs too. pcs should be having latest version of virus scanner u should scan every floopy and cd before use. ram should be of 128 kb or more.