CS5.5 should be able to open ID 2.0 files, but you'll have trouble finding a legitimate copy of CS5.5 anywhere.
The current version is CS6, with the new cloud-only subscription model version InDesing CC due in a matter of weeks. Your current version does not qualify for any sort of upgrade pricing (nor can it be used to activate a CS5.5 upgrade version, if you are thinking of tryoing to find one of those on the auction sites).