Still is a very capable machine you've got there. If I look at the specs of your mobo, it says it is compatible with DDR400 (PC3200). Are you sure you have PC2700? You may have PC3200 and this mobo support no higher than that.
Anyway, the RAM is probably the only thing I would add to. One more gig wouldnt hurt. But if I were you, I would save the money and wait for next year or a couple of months to upgrade this PC. I mean, the CPU is pretty good and latest socket, the video card isnt outdated...
Three months ago I wanted to upgrade from a:
3ghz 533mhz fsb s478
1 gig PC2700
radeon 9600xt
but I thought this was still too good to just let the parts I wouldnt use in a closet. So what I did was, I took a case, dvd-rom, cd burner, floppy, hard drive, all spare parts, assembled them with the mobo, cpu, video card, ram and sold it for 800$CAN. So now it wasnt lost money
I then could buy :
3.4ghz lga775 2mb cache
1gig ddr2 533mhz (intend to buy 2 more gig in the next few months)
radeon x850xt 256mb
maxtor sata 250gb
for about 1700$CAN. that means I upgraded my pc for about 900$CAN out of my pocket at that time. Pretty good huh? Got money back for parts I wouldnt have had money for at the first place.
You could do the same thing if it pleases you. But if you do, search in stores near you and sites on internet for lowest prices (dont forget to calculate the shipping). If you dont have spare parts you could buy some.
Oh yeah and dont build the system to sell before having a buyer... ;) I sold it before it was assembled... heh heh that way I wouldnt have made it for nothing should have I not sold it.
So if you choose that option and need further assistance, give me a nod and I will be glad to help. :D