Try this:
<?php
#### Generated by Block Creator by Astalavista-BD (
www.phpnuke-downloads.com) ###
if (eregi("block-Paypal.php",$PHP_SELF)) {
Header("Location: index.php");
die();
}
$content = "<center><form action=\"https://www.paypal.com/cgi-bin/webscr\" method=\"post\">";
$content .= "<input type=\"hidden\" name=\"cmd\" value=\"_xclick\">";
$content .= "<input type=\"hidden\" name=\"business\" value=\"******************\">";
$content .= "<input type=\"hidden\" name=\"item_name\" value=\"**************\">";
$content .= "<input type=\"hidden\" name=\"no_note\" value=\"1\">";
$content .= "<input type=\"hidden\" name=\"currency_code\" value=\"GBP\">";
$content .= "<input type=\"hidden\" name=\"tax\" value=\"0\">";
$content .= "<input type=\"hidden\" name=\"bn\" value=\"PP-DonationsBF\">";
$content .= "<input type=\"image\" src=\"https://www.paypal.com/en_US/i/btn/x-click-but04.gif\" border=\"0\" name=\"submit\" alt=\"Make payments with PayPal - it's fast, free and secure!\">";
$content .= "</form></center> ";
?>
Fill in your Paypal account info in the appropriate spaces. Save the file as block-paypal or something similar, upload to your html/blocks folder, then activate the block in your sites Block admin panel.
I didn't fill in my account code but I think the block itself works fine. If you want to see what it loox like then just look on the top right of the page, under the header here:
http://www.gamemoviemaking.com
Hope this helps.