html - Horizontal list items

Question

So, I have attempted to create a horizontal list for use on a new website I am designing. I have attempted a number of the suggestions found online already such as setting 'float' to left and such - yet none of these have worked when it comes to fixing the problem.

    ul#menuItems {
      background: none;
      height: 50px;
      width: 100px;
      margin: 0;
      padding: 0;
    }
    ul#menuItems li {
      display: inline;
      list-style: none;
      margin-left: auto;
      margin-right: auto;
      top: 0px;
      height: 50px;
    }
    ul#menuItems li a {
      font-family: Arial, Helvetica, sans-serif;
      text-decoration: none;
      font-weight: bolder;
      color: #000;
      height: 50px;
      width: auto;
      display: block;
      text-align: center;
      line-height: 50px;
    }

<ul id="menuItems">
  <li>
    <a href="index.php">Home</a>
  </li>
  <li>
    <a href="index.php">DJ Profiles</a>
  </li>
</ul>

Answer 1

Updated Answer

I've noticed a lot of people are using this answer so I decided to update it a little bit. If you want to see the original answer, check below. The new answer demonstrates how you can add some style to your list.

ul > li {
    display: inline-block;
    /* You can also add some margins here to make it look prettier */
    zoom:1;
    *display:inline;
    /* this fix is needed for IE7- */
}

<ul>
    <li> <a href="#">some item</a>

    </li>
    <li> <a href="#">another item</a>

    </li>
</ul>