\"I\'d like to invest in a sound library that I could run to Gigastudio inside of Protools\"
I don\'t think you can run Gigastudio \'inside\' of ProTools, but it may be possible to run it on the same machine as the PC version.
\"I\'m reading with great interest about Garriton, Vienna Orchestra, etc.\"
They are popular and respected libraries, but priced at opposite ends of the market. Perhaps if you can be more specific about your budget or requirements, others here can help \'narrow the field\' for you.
\"AND the Akai Z8 sampler I have wants to read \"Dot Wave / Native File\" format, I am told.\"
No problem. Gigastudio has an Akai converter which will convert certain versions of Akai library into native Gigastudio files. Gigastudio also uses .wav files as its basic form of \'sample currency\' when building a patch. If you need to convert more exotic formats, Translator, CDxtract and Awave are 3rd party converters which all have different strengths.