Agilent's web site lists which version of software is compatible with which version of Windows you have. Older computers like 486 and Pentium 1 use the 82335 HPIB/GPIB board while Pentium 2 through 4 use 82341 or 82350 GPIB. As to very-new computers, I don't know if those can take those newer GPIB; Agilent uses LAN interfaces these days. So it's not as straightforward as you think. We were given Y2K software A.06.03 free by Agilent in Dec. 1999, and still run a few of those on Windows 95. Your license number remains the same when you update your software to a newer revision. A license number for G2170AA won't help you if you want to use on a GC - you'll need a GC license number. If you use A.06, you likely need Win95 or Win NT 4.0; I think we run one unit with A.06 on Win2000, and the only issue is we get an error box to click on when we open "online instrument" or "offline instrument". You say you want to upgrade to version A.06; if your instrument is already computerized, it should already have a license number, pasted on its side, or you can write down after finding it in the software. So, if you have that, and the same computer is already Win95, all you would need would be the A.06 CD. And if you attempt to go up "too" high, you might also face firmware issues. May I ask what reason you want to upgrade to A.06, and from what version?