Fencer,
you could gain a good bit of performance by cleaning up your processes/services being used
your pagefile numbers are: Page File: 747MB used, 4204MB available
a good clean / tweaked windowsXP system should be around 200 MB used or less and at startup & sitting idle you should have around 18 to 21 processes running
Karaya also had a good point on either removing 1 of the 3 1 GB sticks or adding a 4th 1 GB stick of Memory, so you could run in Dual Channel mode.....
I recently threw together an AMD system that had an ASUS AMD board with the AMD Athlon 64 X2 Dual Core Processor 6400+, 3.2GHz (Black Edition)
and 4 GB of memory running an ATI HD3870 with 750 watt PSU........ it could damn near run the game maxed out using hirez pkg screen res was 1280x1024 and texture shadows was 2048
but I used Windows 7 64 bit Ultimate for the OS ( most of the parts were used....... just bought a new MB so the person could upgrade to an AMD AM3 processor if they ever wanted to
so either clean up and tweak the windowsXP and work out the RAM issue and possible upgrade your video card............. and just going from experience, I would use an ATI videocard since both your northbridge & southbridge are AMD/ATI chipsets.... instead of nvidia(nforce) bridge chipsets....... you might gain some performance there as well.....
and you might could gain even more if you upgrade the OS to Win 7 Pro 64 bit ( just my personal preference but I would not use the home/home premium versions......... I always recommend the Pro if not the Ultimate 64 bit, for the RAM allowed/accepted quantity gets a significant increase going from the home version to the Pro or better Win 7 OS'es )
I did tests back then when I first was testing Windows 7 64 bit over WindowsXP Pro 32 bit on a similar build as I posted above... the windows 7 outperformed the windowsXPPRO by 15 to 20 fps....... and I had my processes tweaked to 18 on the winxp os ( the system was setup for dual boot ) think I even posted about it here in this hardware forum....... back in 2009
edit: your monitor settings look strange to me:
Current Mode: 1920 x 1080 (32 bit) (60Hz)
Monitor: Plug and Play Monitor
Monitor Max Res: 1600,1200
current says you running at 1920x1080 but Monitor Max Res says it should only be 1600 x 1200......... if you are "forcing" either the monitor or the video that could cause you some performance possibly........ just assuming here......
hope this helps...... best of luck to ya
TC