Newbie ?'s

I'm in the process of upgrading my equipment. This will be the best I've ever heard at this point. Here's what I'll end up with. Adcom 555 II, Klipcsh kg3.5, and a Paradigm pw-2200. I mostly listen to hard rock so I know that I like in that genre. I really like guitar in any fashion. But what I really want to know is are there any "must have" or "reference" cd's for a higher end system? All styles considered.
I've always liked Steely Dan's Aja, Blood Sweat & Tears' self titled album, and Pink Floyd's Dark Side of the Moon (recently re-released as a CD/SACD hybrid) for good sound. Of course, they've done a good job remastering the Stones' albums in hybrid format, too. Other re-releases include Michael Jackson's Thriller and Weather Report's Heavy Weather. Looking forward to suggestions from other Audiogoners.
I too like Steely Dan. A must have for any system that can rock is Jethro Tull's Living in the past. The MFSL set is by far the best you can get. Sonic Heaven !!!!!!
Frank Zappa is a-must for every guitar lover. Any of his albums are more than great. The well recorded ones are "Jazz From Hell", "Broadway", "Ship Arriving Too Late...".
King Crimson "Islands", "Discipline" and "Starless and Bible Black".
You can also "experiment" with Praxis' "Transmutation" which is Bill Laswell's project with the hell of the guitarist Buckethead. Excellent recording on Axiom CD with blend of heavy punk, funk, jazz.
for rock guitar:Robin Trower:Bridge of Sighs (remaster)
Given your stated tastes and the fact you don't mention vinyl in your new setup, I would second the recommendation for the recent reissue of King Crimson's "Discipline", as well as their live "USA" and "Red", all HDCD reissues. Lots of other good suggestions above as well.

You may also find Dream Theater's "Scenes from a Memory" and "Six Degrees of Inner Turbulence" good.

If you like instrumental rock and virtuoso players, I would highly recommend Liquid Tension Experiment (both Vol. 1 & 2), as well as Planet X's "Moon Babies".

Finally, when you need a break from the volume, I would offer Jane Monheit, "In the Sun", Trio Da Paz, "Cafe" (you'll have to google them to find their site), Peter Gabriel "4" reissue. A harder to find release, Mark Levine and The Latin Tinge, "Isla" is very well produced (especially for a small, local release).
Peter Gabriel "SO" Remastered is a must have IMO