I've currently got a amd3500+, 1gb ram and a 7600. It's been working well since mid 05 apart from the old vid card dying, however its getting to the point that i cant play many new games on decent settings and the hdd failed a few weeks ago so its probably about time to upgrade.
108595 Intel Core 2 Duo Processor E7400 2.80Ghz 3M 1066Mhz LGA775 $255.14
107710 ASUS P5K SE/EPU Intel P35 LGA775 ATX 1600FSB Core 2 Quad & Core 2 Duo, Dual-channel DDR2-1200/1066/800/667, 1x PCI-E x16, 2 x PCI, 4*SATA, 12 x USB 2.0, Gigabit Lan $167.63
106481 Corsair XMS 2GB (1GB x2) DDR2-800 XMS2-6400 2x128Mx64non-ECC 240 DIMM, unbuffered, 4-4-4-12, 64Mx8 DRAMs, E.P.P. Technology, matched pair, with Heat Spreader $87.75
107420 Western Digital Caviar GP 500GB 7200RPM 16MB SATA II HDD (WD5000AACS) $122.63
108130 Palit 9800GTX+ 512MB 256Bit DDR3 PCI-E TV-Out Dual Dual-Link DVI HDMI $380.25
~1k NZD
prices from qmb
I'm looking at something like that so far, but not sure about whats good at the moment.