Searches in Outlook 2007, at first glance, have become cumbersome and difficult to use.  That's not really true - you just have to take the time to figure out how they work.

My problem was that I use Outlook to help me remember what I worked on in any given day for the purpose of my billing.  What I used to do in Outlook 2003 was search using the advanced search (Ctrl-Shift-F or Tools-->Instant Search-->Advanced Find) , select the "Advanced" tab and enter "From" and a date and "To" and a date to find all emails on a given date.  It worked great, because by default, if my inbox was selected, the default search included subfolders. 

But that's not true in Outlook 2007.  In Outlook 2007, the "Search subfolders" option is NOT selected by default, and, as far as I can tell, it's not something I as the user can set.  That was quite irritating, as I'd always have to click "Browse", select "Mailbox" and then select the "Search Subfolders" option.  I'd wanted to create a search folder, but my criteria aren't static - I need to change the date based on what day I'm trying to remember what I worked on so I can enter my billing correctly.  It took some working on it, but I've found what turns out to be an even easier way than using the advanced search.  It's called instant search and it uses the Windows Desktop Engine inside of Outlook to instantly search your email.

First, notice above your inbox, there is a box labeled "Search All Mail Items".  See below.

Search bar

Click the left, black, drop down arrow.  This will bring up the search options screen.  If you want all folders included by default, make sure the "All Folders" option is selected and click OK.  See below.

Search options screen

Next click the right, double arrow drop down in the "Search All Mail Items" area.  You should see a screen similar to the one below.  You can also get the screen to open using Ctrl-Alt-W.

Search screen

Regarding the highlighted areas:
  1. If you want to add fields to the search that are not shown, click the "Add Criteria" button labeled 1 and select the field to add.
  2. By clicking the drop-down associated with a field name (i.e., #2 [body] in the above photo), you can choose to remove the field or change the current field to another field.
The searches are dynamic - as you type, the search runs, so you may see a few flashes in the results.

If you're a keyboard shortcut sort of person, and I am, is that after you run a search, in the search box at the top, the search criteria is entered.  So, in the screen shot below, I can simply type my search criteria quickly and easily in the area highlighted by the rectangular area or enter the values into the drop down boxes.

Search by entering text

That's basically it.  It turns out that it's actually easier for me to search by date in Outlook 2007 than it was in Outlook 2003.  After upgrading, things change, and it's not always easy to figure out a new way to do an old task.  But the time spent was worth it!