alsje http://codex.wordpress.org/Category_Templates

Different Text on Some Category Pages
A slightly more complex possibility is that you want different text to display depending on which category page the visitor is viewing. Then you would add the "default" text to the main category.php file, and create special category-#.php files (with their own version of the text, as described in the Introduction) for each category that needs special text at the top.

This does however create a lot of files in your theme directory, and can be avoided using the following code OUTSIDE the loop:

<?php if (is_category('Category A')) { ?>
<p>This is the text to describe category A</p>
<?php } elseif (is_category('Category B')) { ?>
<p>This is the text to describe category B</p>
<?php } else { ?>
<p>This is some generic text to describe all other category pages,
I could be left blank</p>
<?php } ?>

This does the following. C
hecks to see if we are looking at Category A, if we are then show the first bit of text, but if we're not then check if we are looking at Category B. If we are then show that bit of text, and finally, if it is neither Category A or B, then show this default text.