replacing multiple spaces with one

Hi all (easy one - I think) I need to replace all instances of multiple spaces in a string with a single space. I tries the following: $ArticleText = str_replace(' ', ' ', $ArticleText); but if I have four spaces, I am left with two - this is wrong... I am sure that I am really looking for a ereg_replace or preg_replace, but having no c/perl programming background, I do not know either perl or standard regex syntax. Could someone tell me what the correct ereg/preg expression for this would be? I would also like a pointer to regex syntax, if someone knows offhand. Thanks David R