That's too low. Windows XP needs at least 128 MB to boot up and run by itself. A rule of the thumb is to double the memory if you're running Windows XP or Service Pack 1; triple that figure if you're running Windows XP SP 2 and the latest security hot fixes. More RAM will make a computer run faster and keep Windows from freezing up or crashing as often. A RAM module or two can make a lot of difference performance-wise and its the most inexpensive way of upgrading a PC.
(Denny Crane: "Sometimes you can only look for answers from God and failing that... and Fox News".)