128MB Graphics card and 1GB RAM if you can, don't waste money, check you settings.
If you have Athlon <XP3200+ 333 FSB then you should only get DDR333 (PC2700) if you don't plan on upgrading to Athlon 64-bit any time soon.
Athlon XP3200+ 400FSB = DDR400 (PC3200)
If you do plan on upgrading to Athlon 64-bit within 12 months then I would suggest getting the fastest memory you can, as the FSB speed is 1600MHz, anything near PC12800 would be nice
Think the fastest available is PC5300 from Corsair.