There's been a lot of discussions on sRGB vs adobeRGB so if you wish to know more about these, just google. I've listed a couple here and here:
Notice the sRGB version has more punchy colors whereas the aRGB version has duller/pale colors? You won't notice any difference though if you are using Firefox 3.5 or Safari in Mac. In fact, the colors might look even nicer as aRGB has wider gamut than sRGB, only it won't display well on non color-managed browsers.
Sorry for the small images but i want them to appear side by side for easier comparison. You can always click on the image to view the bigger versions.
If you use ACR, make sure you set the color profile to sRGB (red arrow)
If you use DPP or Capture NX, make sure you set the color profile in your camera to sRGB. It does not matter though if you shoot in RAW and use ACR for your RAW conversion as ACR will ignore your in-camera settings.
NOTE: If you're using Firefox3.5 or Safari on a Mac most likely you won't have any problems as both color profiles will display properly. However, you should still convert your images to sRGB though because majority of the viewers can only view sRGB correctly.
All macro images shot with a 40D, Canon MP-E65 1X-5X Macro Lens and Canon MT-24EX Twin Flash
It is also important that you have your monitor/display calibrated at least once a month. I use Spyder2Express to do it.