Currently I am running a Q6600 with 4gb ddr2 1066 ram. I use my drives just like you say apps/storage. However, I am using CS3 (when does CS5 come out?). My hard drive bogs down b/c I have Chrome, Picasa, Bridge and photoshop open. The main time it really bogs down is when I run actions and have a folder of pics open (around 20-30) in Photoshop.
So, b/c my bottleneck is my hard drive wouldn't it be better to try and go with an SSD first?
OH. CS3 is Ghz friendly, not core friendly. Meaning, for CS3 you want higher Ghz rather than more cores. You'd get better performance out of a dual-core e8400 running at 3Ghz than you will that q6600 running at 2.4Ghz.
So if you are sticking with CS3 for the time being, I'd just overclock that Q6600 to over 3Ghz (if you can) and that will make a world of difference. If you upgrade to CS4, it will automatically just be quicker without you doing anything since it makes way better use of multiple cores/threads. I assume CS5 will be the same improvement.
CS5 "should" be out this year. They've been launching a new version every 18-24 months, so that puts them in 1H 2010. There is a site called cs5.org which I have no idea if its legit, but they've been posting previews/news up there for a few months now that certainly seem like they're real.
A few questions...
When you run these actions, do you run them from the folder or on images currently open. If you open up the files, run the action and it takes a while.... then you're CPU and maybe RAM limited. If you've set the action to run through a folder processing a bunch of files (i mean bunch like 100+) then hard drive may be your limit. The only headache would be you'd have to move the files you're working on to the SSD and then move them back to storage when you're done (since the SSDs are so small).
Is it only slow when you have all four programs open? What if you just run the actions with only PS open... is it any different? If it is, then clearly you just need more RAM.
When you've got all 20-30 images open what is the scratch size? If you've never looked it up, in the lower left corner of a document window click on the fly-out menu and choose scratch sizes (not document size). This gives you how much RAM memory you have available, and how much you're using. If you go over the amount of RAM available then you hit the hard drive as a scratch which is *painfully* slow. The easy (and cheap) solution is to add more RAM.
How big are these files, and what format are they typically in?