CS4: Super Slow Redraw on Windows 7

Question

Hello all,
Photoshop is running very slowly, even with tiny files (50k). I haven't had the need to run large CMYK files as yet, but I am guessing those will drastically slow the already molasses-like redraw. When I say redraw, it's actually the rulers that are taking the longest to render, after which the actual artwork appears.
Photoshop settings:
Photoshop is using 75% of my system's resources
'Available RAM' = 1603MB
'History States' = 30
'Cache Levels' = 4
Compatibility = Windows XP (Service Pack 2)
Windows Settings:
Virtual memory: check (per Adobe's instructions)
Scratch Disk: check
'Enable Open GL Drawing': check (off)
Hardware:
Dell Optiplex GX 620
Intel 3.00GHz
4.00GB RAM (3.5GB usable)
32-bit OS (Windows 7 Ultimate)
I did not experience any problems installing Windows 7 or CS4. Neither crash or are glitchy in any other way... I spend 90% of my work day in PS, so it is mandatory, for my personal sanity and productivity, that PS run as fast or faster than when installed on XP.
I've attached screen captures of my PS preferences/performance and the Windows 7 basic info dialogs.
Your help is appreciated!
TIA,
Mark

Answer 1

All, thank you for your replies. I apologize for the delay in responding - I have been swamped.
dec9 wrote:
Change your scratch disk to D drive.
Update your video card drivers.
your video card not up to snuff with opengl?
also why are you running CS4 in XP service pack 2 mode for?
There's plenty of space on the C drive and that's the drive PS is installed on... is there a reason I should change to D?
Video card drivers are current, however, it's a 256mb unit. I went to my local Fry's and picked up a Radeon 4670 and 500w power supply only to find that both are too big for my Dell Optiplex. Argh! Now, not only am I still lagging a little (read below for the semi-solution), but I have to stand in that dern Fry's 'returns' line.
I was trying all the different compatibility options hoping one would resolve the issue...
Thanks again for your input.