ArcIMS died April 11, 2007, the day Arc2Earth Publisher was released. With the ability to serve up even dynamic layers using Virtual Earth, there is no reason to invest any money in ArcIMS anymore. Save the money you would be using licensing ArcIMS and take a look at ArcGIS Server which does bring the promise of modern functionality to ESRI map servers. I mean wouldn’t you rather have this (via Virtual Earth Blog):
By not being able to serve up tiles, ArcIMS is slow, outdated and ugly. Time to move on (and I say this with great regret because I’ve rolled out more ArcIMS sites than I can remember over the years). Invest your time and energy in ArcGIS Server as well other more modern web mapping servers.
Putting ArcIMS to rest