Re: What's holding back my PC?
32 bit Windows can handle up to 4 GB of total system memory (total as in everything even the memory on the video card). Windows divides up your memory so it can allocate portions of it for specific tasks and because of this it doesn't always show the full amount, sometimes it will only report the "use-able" memory or the memory that is available for programs.
I think your power supply is responsible for any black screens or sudden restarts. Though you should go ahead and clean out all of the dust with a can or 2 of compressed air. Don't use a vacuum as it can suck up the small jumpers on the motherboard and then you will be screwed.
Your cpu is bottlenecking your system, but even if you replace the cpu with the best available for your motherboard you'll still be backed up. I'm thinking the Pentium D came out when the LGA775 socket 1st appeared and your motherboard won't support any of the newest models. I hate to say it but the system you have isn't worth spending money on unless you buy a new mobo, cpu and some faster memory (DDR2 800 or 1066) plus a new power supply that you need already. I would start saving up a few dollars.