oH!  sounds like fun. Well,       I wouldn't worrie with defrag "just my opionion".  I would start with the exchange server and make sure that it is all up to date w/ patches and such. Another thing is when you are getting mem. errors and blue screens. I wouldn't count out hardware issues.   good luck ...  and let us know how it goes. Oh...   depending on the $$$ flow .. if you can I would seperate the sql stuff from the exchange.