Photoshop should not take 4 minutes to load with your current hardware. Sounds like you have some software bugs. Restart your system, then go to task manager and look at your memory usage under the performance tab. That number should be 1.5GB or less. If it's more, then you must have a lot of background apps running (remember to check this on a fresh reboot) which will slow things down.
Upgrading to 64bit will help some as well.
Also to comment on what hardware will speed what up...
Your videocard's GPU (graphics processing unit) will accerlate OpenGL or DirectX applications when 3d polys, 3d lights and draw calls are used (games and 3d apps). This can also include, some GPU powered features in Photoshop and any GPU filters in Pinnacle Studio **if applicable**.
The load time of your apps are mainly limited to the speed of your hard drive. I'm assuming you have 7200rpm HDDs, but Windows can get bogged down over time and it may be time for a reformat.
Your memory speed is only 800Mhz, but this is about average. More memory will only allow you to load more images at once in photoshop and will pervent it from being bogged down depending on the amount of memory you have. But more memory is not going to "speed" up photoshop.
When you start adding filters and start tweaking images in PS, your processor will handle this. It's nice that you have a Quad Core, but without a 64bit OS, you're only using 2 cores (4 multi cores if you have hyper threading enabled). Switching to 64bit OS will give you full access to your 4 cores (8 multicores if you have hyper threading enabled).
You editor is more limited by your hard drive speed and how fast your footage can be loaded as well as your processor during video playback/previewing. If you're editing HD footage, your 4GB of memory can get full pretty quickly.
Also, once you're in the midst of a editing project or in photoshop, and things are running slow, check task manager again and see if your 4GB are used. Also check on your CPU usage... some background apps will use a lot of processor power.
Be carefull about having anti-virus software on your editing machine... this can kill performance to a unrealistic level.
1) Upgrade to 64bit OS
2) Check your bios settings and be sure hyper threading is enabled
3) Upgrade to at least 8GB of memory.
4) New videocard (get a GTS or GTX model)
Let me know if you have other questions.