Skurj it's very likely not the OS but something else..
I've used W2k for over a year for gaming and business use and I've never had problems with anything except the old games (pre-98 technology.)
It's generally a bad idea to have your LAN card sharing irq's. Change your soundcard to another PCI slot, that should fix the problem. Find a PCI-irq map for your motherboard so you know which pci slot is using which irq.