Ever notice that the ratio of system memory to video memory is always 4:1 for the highest-end systems?
1999: 500MHz Pentium III, 128MB RAM, 32MB TNT2/GeForce 256
2000: 1GHz Athlon/Pentium III, 256MB RAM, 64MB GeForce2 GTS/Ultra
2001: ~1.7 Athlon XP/Pentium 4, 256MB RAM, 64MB GeForce3...