You could solve this 2 ways, one would be to create rows with a fixed height like you propose, the other solution would be to create a big table with 3 columns where you remove the borders from the middle column so it looks like 2 tables.
The solution you were asking for could be as follows:
<style>
td { vertical-align: top; }
td div { height: 40px; overflow: hidden; }
</style>
<table width="400">
<tr>
<td><div>short content</div></td>
<td><div>long content long content long content long content</div></td>
<td><div>long content long content long content long content</div></td>
</tr>
<tr>
<td><div>long content long content long content long content</div></td>
<td><div>short content</div></td>
<td><div>long content long content long content long content</div></td>
</tr>
</table>