This kind of graphics card slot isnt used any more . The good news is that an 8x AGP graphics card should work . The bad news is that there are limited choices because they are not made anymore [ maybe just a few ] .
I would buy a second hand card on an auction site or go through the parts bin in your local computer shop . The rest of your computer is pretty old in computer terms so its not worth spending any more than you need to just to get it running again . $20 max .
The card you have now is an MX 400 . Why do you think it needs to be replaced ?
A-DATA 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model ADQVE1B16K - Retail
Seagate Barracuda 7200.10 ST3160815AS 160GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM
LG 22X DVD±R DVD Burner Black SATA Model GH22NS30 - OEM
Can be improved easily by switching the CPU to a Kuma 7750 X2, and adding a video card. The PSU I've listed will have no trouble with a 4670, which needs no auxiliary power, or a 4830, which does. Change to an Antec Earthwatts 430 to run up to a 4850. The Thermaltake 430 in IH8U's list is not too bad, but is over-rated. It's really a 350W-375W PSU, which is too small for a 4830.