Can someone explain the differant CD formats?

I was looking on the Acoustic Sounds website, and many jazz CDs are listed as: CD, DTS CD, Gold CD, HDCD CD, XRCD CD, etc. I would like to purchase some of them, but are they compatible with my inexpensive Cambridge 540C V2 player?
Don't forget SHM-CD (which is compatible)

All those you listed are compatible with a regular CD player.
The only ones that would not be compatible with your CDP are SACD and DVD-A (DVD-Audio).
HDCD stands for "High Definition Compatible Digital" and was developed by a company called Pacific Microsonics, Inc back in the late 90's to improve the overall sound of conventional CD's . The technology was then acquired and purchased by Microsoft who now licenses the technology to specific record companies who choose to produce their CD's in this format. Sound is greatly improved by packing more "information" into conventional CD's with a standard sampling frequency of 44.1kHz and 16 bits per sample. CD players which do not decode HDCD will produce somewhat improved sound of an HDCD CD but those players which do decode it will sound far better!! I know. I have the Rotel RCD-1072 CDP which does decode and I'm building my CD collection of HDCD's. They are without a doubt far more enjoyable with greatly improved soundstage, bass depth, detail, etc. Certain artists such as Joni Mitchell and the Grateful Dead are reproducing their CD's in this format. It's especially useful on the older recorded albums. You'll also find some smooth jazz artists with HDCD's such as Dave Koz and Brian Culbertson using this format on "some" of their CD's.

DTS stands for "Digital Theater System" and is a format used in Surround Sound receivers and processors. It's a competing surround sound format to Dolby Digital. If a DVD is formatted in DTS and you play it back in DTS, it will sound its best. Honestly, I've never heard of DTS CD but my guess is that the music on the CD is encoded in DTS so it would be best to play it back using a surround sound receiver in that format. Gold and XRCD I'm not familiar with. Another competing high def audio format now is called SACD (Super Audio CD's). These are supposed to sound superior to even HDCD's and the players are generally more pricey than those with HDCD. The Marantz SA8003 CD player is one good example.
XRCD is a process (check though JVC USA sold its ops to a retailer 2yrs ago). It will be fine on any CDP.

HDCD requires a decoder chip I believe (or software decoding within the playback software) to get to the HDCD dithering algo and filters, though I expect HDCDs are playable on your CDP anyway.
DTS Cds *require* a DTS decoder somewhere in the output stream. I do not know of ANY CD-only players that have this capability. Almost all DVD players incorporate a DTS decoder. So, if you want to playback DTS CDs, you need either a DTS-capable DVD player or a CD player connected to a DTS decoder, usually found in most pre-processors and AV receivers.

The really cool part about DTS CDs is that they are multi-channel capable. I just bought a terrifically good Telarc DTS CD by Junior Wells, "Come n In This House". If you have a surround sound system, you MUST hear this title, it sounds fabulous.

Don't forget about CODE promoted right now by many artists - it's 20bit/96kHz recorded on DVD.

As for HDCD - it cannot play better on regular non-HDCD player. It uses least significant bit to switch dynamic range of remaining 15 bits (in-band signaling technique) and if player doesn't decode this bit you'll get 15 bit music with weird dynamics + 1 bit garbage.