I purchased the Alldata CDROM a couple of years ago. It covered only through the '95 model 850 and I don't think that it is available any longer. I understand that the online service has essentially the same information and format as the CD. I have found the CD to be a useful supplement to my Haynes manual. Where one is weak, the other often has what I need. The diagrams Alldata has are especially useful. In fact, it looks like some of them may have been copied from the Volvo shop manuals. It's been handy to be able to access the TSD's as well. I've implemented a number of the fixes described in TSD's.

From your earlier postings it's clear that you're exploring many of the same things I did when I bought my first 850 (cabin air filter, air pump control valve, Alldata, to name a few). From that perspective, I'm sure that you'd get use from the Alldata service. It would be even better if I had a laptop computer with wireless Internet service so I could consult it as I work on the car!