Hard Drives: Read/Write vs. Buffer Size?

I'm a designer (web/print) so I've always got Photoshop, Flash, Dreamweaver, too many fonts, and other various stuff open at once.. The G5 I'm using is Dual 2 GHz with 5 gigs of RAM and using a 7,200 rpm/8MB cache hard drive (Maxtor 6Y250M0)...

I've been having the problem where if you switch from one program to another, that program you're switching to lags (spinner wheel while interface loads up again)... This even happens if I'm just trying to save a file (spinner wheel....................aaaaaaannnnnnd.... ok it saved - thank god)...

I know I could close down some unneeded programs, deactivate some fonts fonts, etc (which i need to get into the habit of doing).. but i was curious if getting an upgraded hard drive would help that situation which brings me to Read/Write time (WD's Raptor 10,000 rpm) or Buffer Size (say WD's Caviar Black 32 MB buffer) (NOTE: not saying I'm getting those.. just examples... haha, after reading posts - seems many are touchy about the hardware they use/recommend)...

I'm just out of space in general and need quicker drive with more room.. just curious if you guys could give me any insight... if neither matter, I'll just go across the street and grab a drive..

thanks guys!

 

@ kastenbrust: I'll look into those... any suggestions? not really trying to break the bank on a drive - but.. then again.. it's work related and would probably be worth it...

@ melchior: i haven't really thought about a scratch disc - though, would probably make sense. either way - i need to snag a new drive due to space issues.. may just order some RAM while I'm at it and just max it out...

just for the hell of it, here's a quick grab of the activity panel (i hope i'm just being impatient - not going to pretend i know what ALL this means) :

Active Memory: 2.20 GB
Free Memory: 1.92 GB
Wired Memory: 436.54 MB
Used Memory: 3.07 GB
Inactive Memory: 459.68 MB
Total VM: 43.59 GB
Number of processes: 60


thanks for your time guys.. much appreciated...