Most NICs manufactured after 2004 support <a href="http://en.wikipedia.org/wiki/Auto-MDIX">Auto-MDIX</a>, which means that most of the time, you should almost never need to use a real crossover cable.

<p>Nice features:
<ul>
<li>Only one side needs to support Auto-MDIX for it to work, both sides don't need it.
<li>The Gigabit standard <i>requires</i> Auto-MDIX support, so every Gigabit NICs should support it.
</ul>

<p>Gotchyas:
<ul>
<li>Auto-MDIX is a feature that can sometimes be disabled, so you may need to enable it for a particular NIC first.
<li>If you enable Auto-MDIX, then everything else has to be auto-negotiated too (e.g. speed, duplex).  On professionally configured networks, auto-negotiation is a no-no, so Auto-MDIX shouldn't be used there except on a temporary as-needed basis.
</ul>