I've noticed that 12.2.44-SE6 is listed as the latest available IOS for any Catalyst 3550 except 24 DC SMI (12.2.55-SE8 available for that one). Does this mean that nothing after 12.2.44-SE6 won't work properly (or at all) on most C3550 models? I'm asking this because I've just come across a C3550-12T in our network running 12.2.52-SE (apparently without issues - weeks of uptime)...
The latest image on CCO for 3550-12T is c3550-ipbase-mz.122-44.SE6.bin
I would not put an image on a device that is not on CCO and probably not supported.