Need faster hard drives

ok... i am lookin for some info on what hdd is hould get for my comp.

my comp is mainly used for dowloading\watching videos and playing games.
my current setup is a IDE 80gig 7200rpm seagate that has windows and all my programs on it and a SATA 750gig 7200rpm hdd that has my 'My Documents' folder on it, so all my videos, music, pics and downloads are all on that one drive.

i only recently got the 80gig because i was running out of space on my 750gig, consequently it was making my comp slow( or so i was lead to believe) and my friend was giving his 80gig away.
i thought this would make my comp faster, but in fact has made it even slower and more problematic. i personally think it is because i am using an ide drive as my processing drive.

i wouldnt call myself a noob exactly, but when it comes to this i find that i dont really know what is best for what i do with my comp, and i am hopeing to get some insight into this matter from u guys.

i guess my main question is should i get a 10000rpm 16mb cahce drive or a 7200rpm 32mb cache drive to replace the 80gig. i am wanting to stick to my current setup so this drive will only be for windows and programs, all storage of music and videos ect, will be stord on another drive in an attempt to keep the main drive as fast as possible.

any info u guys can give me will be much appreciated. and plz dont just give me specs expecting me to get it. plz be simple a straight forward, but if u find u need to give me specs plx explain them.

thanx alot guyz,
Darkrenzo