What you have is mighty close to the computer that I built for my mother several years ago, and replaced with something a bit newer this last Thanksgiving weekend. Roughly the same CPU and RAM, and also running XP.
IIRC it started off with 256M of RAM, and was at 1G when it was replaced. Most of the time it was at 512M, which was enough at the time to run Mozilla Firefox and Thunderbird, and Word 2000, according to Process Explorer
. As Mozilla products got more porky, more and more RAM was needed to stave off paging. Although my mom wasn't much for multimedia, it could play audio quite well, and lo-res video if need be.
My first question would be about the CD drive, but it looks like you have that covered. You might want to try unplugging it altogether for a while to see if that makes a difference, but that's a long shot. Now that I think of it, if every component is old, something like a keyboard with a stuck key might be sending interrupts and slowing down the system.
The next question is what kind of software is running hidden in the background on your machine, that might slow things down? When I built my mom's old system, I took care to turn off every unneeded Windows service, application pre-loader and anything else that used up system resources unnecessarily. Doing stuff like this is second nature for me after 15 years doing corporate IT, and having to breathe new life into old computers. It might not be as easy for you.
Is the sound card built into the motherboard, or in a separate card? Now would be a pretty good time to pull all of the expansion cards, clean the contacts on the cards and blow out any junk in the slots. IIRC some sound cards used to offload much of their function onto the computer CPU, which not only uses up more system CPU and RAM, but also relies on buggy drivers that haven't been maintained for a long time. If you can, see what kind of sound hardware you have. A new $10 sound card might make all the difference. (Don't forget to disable all onboard sound/modem hardware before you try a new or new/old sound card.)
Beyond that...If you haven't reinstalled Windows from bare metal
, now might be time to refresh your system. IME a bare metal reinstall is the single best way to refresh a tired old PC. If that doesn't work, it may be time to retire the old hardware. If you have any experience with Linux (and even if you don't) you might use it with Linux. There are plenty of Linux distributions that are designed to make the most out of an old PC.