THE SITUATION:
When customizing your Windows XP Desktop, Microsoft gave you the option of 3 Color Schemes (or reverting back to the old Windows Classic style to get more colors).

Blue (the default that 99.999% of users are using)
Silver (a slight bluish tint, but basically colorless)
Olive Green (a drab green that makes 'colorless' seem like a wonderfully exciting option)

THE RECON:
I did some hunting around, and found that there are many options available. These are Themes that are available for download, some for free, and some (like Microsoft Plus) for a fee.

The problem with these is that they are all entire themes. Besides colors, they setup cursors, sounds, and what I found most annoyingly, the graphics! Buttons have been modified to match with the themes (i.e. little gear buttons for an automotive theme). Things like that. Kewl for about 5 minutes.

These themes also require the installation of software (some of which is spyware or just is no help to system performance and stability).

What I also found in my searching, was some other people just like me, who don't want all these customized changes. We just want some different colors, that is it, no fluff.

So I found TGTSoft Stylebuilder. After a few failed attempts, I found a fairly painless routine to simply re-tint the colors of the major screen components, NO graphics changes, NO sounds or pictures, NO cursors, NOTHING but Color.

THE SOLUTION:
I ultimately decided to, and created, the Jewels collection. These are all started from the Windows XP Styles; Blue (for the darker styles) and Silver (for the lighter styles). Once again, only changing the colors.

Available is:
Amethyst (Purple)
Citrine (Light Yellow)
Emerald (Dark Green)
Obsidian (Black/Charcoal)
Quartz (Light Pink)
Ruby (Dark Red)
Topaz (Dark Yellow/Orange)

These, and the three Microsoft Luna styles should be a fairly decent selection.

Regretfully, Microsoft also designed their Desktop to only use Microsoft signed Styles. If you just setup the Jewels files, they will not show up as an option.

There are 2 choices to make this work:

Install one of the XP Theme Packs (mentioned above). (Also, not sure if Microsoft Plus will work, since it IS a Microsoft Product).

Use the Neowin UXTheme patcher to install a modified .dll. This is the cleanest method, since it only deals with a single dll, modified to allow the use of Non-Microsoft Styles.

I am using the later solution on 3 PCs, and have not experienced any problems. Locating the Neowin patcher can be a real pain, so I am including a download for v5.0 here. Or you can try to Google it or search from this:
http://www.google.com/search?q=multi-patcher+v5&start=0&ie=utf-8&oe=utf-8&client=firefox-a&rls=org.mozilla:en-US:official

I make no warranty, responsibility, and provide no support for either the Neowin Patch, or the Jewels styles that I have created. Use of the Neowin Patch may have negative affects on your ability to get support from Microsoft (see Neowin Disclaimers for more information). You may download and use entirely at your own risk. To the best of my knowledge, I am not violating any copyrights. I suggest you read the notes below before using the Jewels collection.

INSTALLATION:
1. Install Neowin or have some other Themes package running that will allow the use of Non-Windows Themes. (I believe the Neowin Installer requires at least XP SP2)

2. To install the Jewels collection, simply extract the files and directories to your Themes directory (usually C:\WINDOWS\Resources\Themes). Be sure to extract "with folder names".
The Themes directory will contain at least the Jewels.theme, Windows Classic.theme, and Luna.theme files, and a Jewels and Luna directory.

3. Once installed, simply Right-Click on the Desktop and Select Options.
  a. Select the "Apprearance" tab.
  b. On the "Windows and Buttons" pulldown menu, select "Jewels".
  c. On the "Color Scheme" pulldown menu, select the color of your choice.
  d. Apply the changes.

NOTES:
1. The Neowin install can be a little tricky. Be sure to follow the instructions carefully. If the installer detects and informs you that you have a Network Installed XP (like I have at work), you don't get prompted to insert your XP CD (and so you can't cancel/ignore it). The dll is automatically restored from the network. Solution (took me quite awhile of trying to defeat the system in order to figure out my own simple solution) UNPLUG YOUR NETWORK CABLE. :P
Once you get the dll installed and have rebooted your computer, you can then plug your network cable back in without Windows trying to restore you file.

2. I did have to set the background to something (I believe I chose black for all of them), so selecting a Color Theme will set you background color to Black. If you want something else, you will need to manually change this. I think most or all other settings will not be affected.
One method that I have found helpful is to create themes (The "Themes" tab). That is, after selecting the color style and basic options like background color, wallpaper, etc., save the Theme (I would save as something like KC_Amethyst_Dragon or KC_Obsidian_Moon, i.e.
Mine_Color_Background). I have at least one for each color. I then work from those to further customize (been awhile since I have manually selected a Color Style).

3. Internet Explorer had me worried for awhile. Suddenly I was getting these 5 little squares on the lower-right taskbar. Not to fret though, those were always there (status place holders, to show things like secure web sites, etc.). It is just that some of the tinting has made them stand out more (higher contrast)…in some cases, much more! But totally normal.

Anyway, I hope you find this of value, and enjoy using them.

Here are the files for download: (Right Click and "Save Target As")
Jewels.zip    UXThemeMulti-Patcher-Neowin-Edition4.zip