New hard drive

Ok so i have this hell of old HD it was a western digital, but it was only 40 or so Gigs. So i got a new hard drive that is a maxtor something or other, and it is an 80 gig. so i just use the 80 gig without slaveing it or the other because i dont think my power supply has the cords for multiple drives. anyway the new 80 gig one is running slower than god and i am pretty sure i put in all my drivers for my mother board and my videocard, but games like WoW and ragnarok are running way too slow like they are skipping or something and this never happened with my last HD so i figure this new one has a proble or its just garbage. can anyone think why it is running slower since it is newer and better? i am probly going to get a new power upply if i cant think of anything. but yeah newb question and i am in AV so terrible grammar....have at me

could be any number of things:
old faulty/data cable (check for 80 conductor)
incorrect jumper/BIOS settings (choose DMA over PIO)
inadequate/lack of cooling (any case ventilation?)

oh, and good luck with maxtor (1 year waranty)

i got the Hd for free XP so if it is garbage i will be able to handle it. but i will check that BIOS thing