Well, x600 is still old tech. I'd get the 700 or 1600 if I were you.
My OLD System, now Mediastation:
Asus A7N8X Deluxe with Barton 2.5 @ 200*11
2x512MB Corsair CL2 PC400
IBM Deskstar 307030 30GB HD, Ultra ATA 100, 7200 RPM + WD something
60GB HD, Ultra ATA100, 7200 RPM + WD Caviar 120GB SATA133 7200RPM + Samsung 200GB Sata150 7200
Powercolor Radeon 9800pro STILL running 4.3 cats, and Arctic Cooling VGA Silencer
Onboard network cards; !!!Win98SE!!! (yes 200GB HDD on Win98 works fine :))
NEW: HP nx9420, T2400, x1600 256M, 1440x900, 1GB, 100GB HDD, XPPro.