Hard drives for new system

hi, im new to THIS part of the forums, i really dont know anything about harddrives,

so i need your guys's help

im a REALLY big user of photoshop, bryce, fl studio, roadrunner, acid, flash, fireworks, lightroom etx you get the point.

i do A LOT of photoediting, music creation, video creation/editing so i need a hell of a lot of storage space.

so i need a few hard drives that i can use to store all this data.

been hearing good stuff from i think its the wd640???

i have around 400$ extra for hard drives, so what do you guys think i should get?

right now i have a pc power and cooling 750 silencer

with

asus Striker II forumla
core2 quad Q9450
Sunbeamtech corecontact freezer w/ scyther s-flex
4gbs crucial ballistix ddr2 800 at 4-4-4-12
Radeon 4870
X-fi fatality titanium (got it for free so whatever hahaha)
and a killer NIC card i got for free.
my case is a NZXT Tempest with red neon everywhere

im not really looking for speed and quick access, more as good space for price/performance.

I hope I am not being rude but thats not exactly fast. I originally had some issues with the Samsung HD753LJ but even set at 1.5Gbps this is what I get:

[img=http://img390.imageshack.us/img390/4761/hdtunebenchmarksamsunghvc8.th.png]

In terms of dollars per gigabyte, its the cheapest in the range of 640-750GB. And when I allowed the full 3.0Gbps it have me a burst of 240MB/s with averge of 110MB/s and minimum of 86MB/s.

you arent using the same version of HDTune so the results are going to be comparable

It should be fully comparable. The benchmark isn't measuring relative numbers, it's measuring absolute transfer rates.