Classical brushes are processor-centric, hence a faster processor would make them faster. On the otehr hand of course blender brushes use hardware acceleration and may benefit from a better graphics hardware as may many other functions. And by all means your planned "system upgrade" makes zero sense with Win XP, no matter what flavor. It's hoplessly outdated and most drivers for it will be, too, resulting in performance loss again and a million quirks. Just get over it and get Win 7 or Win 8/ 8.1.
What Mylenium said. You're beating you head against a wall with XP. Also there were a lot of improvements with the brush engine in CS6. If you do a lot of brush work you should consider upgrading to at least CS6.
thanks guys, I'll look at Windows 7 and finally move on from XP. The learning curve is something that's holding me back, since I don't want to interrupt my daily workflow with trying to learn where everything is in a new operating system - but will be well worth it to have Photoshop running faster.
It's looking like I'll be purchasing the hardware tomorrow. I'll also be moving up to Windows 7.
My main concern will be the brushes - I'm really hoping for them to accelerate when painting.
Example - If I'm painting in a 300dpi document at 16"x12", certain brushes are so slow to render on the screen (they lag). Basically it's impossible for me to paint at this size of a document because of how slow it is.
Can anyone shed light on what would be the best way to improve this - (someone mentioned a faster processor).
I'm currently running a 3GHZ intel dual core processor on a 32-bit windows XP so from my understanding I'm only able to currently utilize one of those cores. I'll be upping my processor to an i5 3.2 GHZ (quad core) on a 64-bit Windows 7 (so should be able to access all 4 cores). I'll also be increasing the RAM from 4GB(733Mhz) to 8GB(2400Mhz). The motherboard will also be a big step up (will be a current Asus board)
My video card will remain as is for now (1GB Radeon 4570 series (or thereabouts). Is this sufficient for CS6? Maybe the new onboard video would actually be better than the ati card I've had for 6 or 7 years.
Thanks for any input guys. Just want to make sure I'm purchasing the right stuff and if it will ultimately spped up my painting process with larger brushes at larger document sizes (300dpi). That's my main concern right now.