I think with selenium 2, you don't need to wait after a form submit using Firefox webdriver.
element.sendKeys("34344343");
webDriver.findElement(By.id("searchSubmitButton")).click();
WebElement columnInPostedPage = webDriver.findElement(By.xpath("//div[@id='content']/table/tbody/tr[2]/td[3]")); //
If content is loaded by javascript after the page is loaded, you can do something like this for the content
query.submit();
long end = System.currentTimeMillis() + 5000;
while (System.currentTimeMillis() < end) {
WebElement result = webDriver.findElement(By.id("content"));
if (result.isDisplayed()) {
break;
}
//Thread.sleep(1000);
}
WebElement columnInPostedPage = webDriver.findElement(By.xpath("//div[@id='content']/table/tbody/tr[2]/td[3]")); //