When annotation layers are present in map services published with the ArcMap image virtual server, the labels from these annotation layers may appear in bold and possess a fuzzy or pixelated outline specifically on Windows 2000.
Image #1 - Output Image from IMS on Windows 2000
Image #2 - Output Image from IMS on Windows 2003/XP
This problem primarily occurs with ArcIMS installations configured on Windows 2000 platforms.
By default, the option to smooth screen fonts on Windows 2000 platforms is disabled.