RealPlayer used to be a horrible media player, but the latest version is actually pretty good and has come a long way. It still tried to force itself to boot up every time with the system but you can now easily turn this off in the preferences, as well as it only checking for software updates when the player is actually running. It does however still try to add an entry into the startup part of the registry without asking, which is a bit naughty, but my virus checker warns me of such actions so I just set it to block the attempts.

I also have to have it installed to gain full functionality from a number of applications I use, or I lose part of the features they have. Premiere and Cleaner XL especially.