For minimal changes to your initial html code and minimal addition of CSS, I recommend the following
1. Remove the P element so that you get
<table>
<tr>
<td width="120" height="43">Email Address</td>
<td width="156" height="43">
<input name = "email" value ="stuff@example.com"/>
</td>
</tr>
<tr>
<td width="120">Event Selection</td>
<td colspan="2"> <select name = "webinar_selection" size="1">
<option>CtrlWORK Personal Efficiency Software 10:30 - 11:30 Wednesday 15.02.12</option>
</select>
</td>
</tr>
</table>
2. Add the CSS rule
tbody
{
vertical-align: baseline;
}
While this may not be what you mean with "line up with the drop down", notice that the meaning of this "lining up with" will now be consistent with whatever you put in the second cell of each row. That is, the bottom of letters such as 'a', 'e' etc (not letters such as 'g') have this line (known as the baseline) aligned with the baseline of anything else you put in there, which includes both text in a text input element with super huge font size and a select element with normal font size etc. That is, layout stays consistent and still looks good.
For an example of this, check it out by adding these rules
input { font-size: 1.5em; }
select { font-size: 1.5em; }
Not that you're likely to have those rules, but it makes it more apparent what the baseline alignment really does.
If you really really are looking for vertical-align: bottom, be adviced that browsers treat some elements differently here. Some treat a select element as having its bottom line above the bottom border and others as having the border included. Since border is NOT included in element height (total height for element is top border + top margin + top padding + element height + bottom padding + bottom margin + bottom border), I suppose it makes sens to treat bottom as being bottom of element not counting border, padding or margin.
And the reason that some treat a select element border as part of the element is probably that they never thought someone would not have it. But it is still possible to remove the border, in which case a bottom alignment would look silly if aligning with the bottom border...
Either way, you'd not get consistent results across all browsers due to these differences. So once again, my recommendation is baseline.