If you are a keyboard junkie, you can easily select a date range by using the following syntax in the search box in any folder:
modified:2/1/2008 .. 2/20/2008
The key is the two periods between the dates, which tells the search engine to use it as a range. You could use "Datecreated" instead of "modified", or just "date" if you wanted to.
If you want to change the search to also use keywords as well, you can use the name: parameter like this:
It's quite powerful once you get used to it.
Select Date Range with the Mouse
If you aren't a keyboard junkie you probably don't want to remember the exact syntax you need to type in, but don't fear - we've got another way to do it. Just open up Advanced search by hitting the F3 key with an Explorer window open (or if you are using Vista pre-SP1 you can use the Search option on the start menu)
Now change the Date drop-down to "Date Modified" and then "is", then pop up the date range box…
Once you have the date range box open, you can just click the first date and drag the mouse to select more dates.
You can even click on the month to select the whole month, or even select multiple months. The key thing is that once you've got the selection how you want it, you need to click somewhere else… it's slightly tricky until you get used to it.
Of course you'll have the best luck if you also put in a filename into the Name box, and select the right folder location to search in.