Chemstation B.04.02 was the last revision to officially support 5890 (specifically 5890 series II check this data sheet for information about that particular revision:
http://www.chem.agilent.com/Library/use ... anding.pdf)
The difference between A and B revs are that A revisions are designed to work with 16 bit operating systems, and B revs support 32 bit. The biggest difference there is that 32 bit operating systems allow for long file names, and the newer revisions of chemstation are more flexible in terms of data processing. That said, many of the features added are to support new hardware (new gcs, new autosamplers, new microfluidic switches) that may not be of use to you using a 5890. If you have the money and you may eventually expand to owning a 6890/6850/7890/7820, or are doing difficult data analysis you should spring for the more expensive newer software. If you're not running complex samples and want to run this with old cheap hardware an A revision might better suite you--I don't know what the price difference is. I also can't vouch for A revisions running on XP, I think they would but you would need to check into that.
B.04.02 was a nice revision that I used for quite some time, very stable. Chemstation has now moved to a C revision (support of 64 bit as well as a change to the Openlab platform--a refresh to the back end of the software that handles security and configuration) so B.04.02 and B.04.03 were the final B revision releases. If there is a price difference B.03.02 was another good stable revision.
