Here's a better, cross-browser solution
alphatrans {
filteralpha(opacity=50);
-moz-opacity0.5;
-khtml-opacity 0.5;
opacity 0.5;
}
The alpha filter is the IE solution. Opacity covers all the others, with a couple of quirky ones for legacy netscape and safari browsers.
To use this for a paragraph of text, use the alphatrans (or whatever name you give to define your class) class as follows
<p class="alphatrans">Place all your text here and it should be medium gray (50% of black) in color. To use a different color than black, add 'color#XXXXXX;' to your class statement.</p>
It's a little more complex if you want to layer your text over other elements on the page. For that you would need to specify positioning (on the page) and z-index (stacking order). Let me know if you need to know how to do that.
Best of luck.
k