Upgrade from Win98SE to ME, 2000, or XP?

System is a 500 MHz AMDk6-2 with 512 MB RAM, abundant hard drive space, and an older motherboard with 3 PCI and 3ISA slots, running on Windows 98SE operating system. Recent device additions now confront IRQ limitations, and “fatal errors” are becoming more inconvenient. Should operating system be upgraded to either ME, 2000, or XP for better resource management? Or, would overhead requirements of ME, 2000, or XP excessively slow down this system to negate any advantages of upgrading? Which upgrade path, if any, would be best?