Win 7 is pretty awesome so far.
Who uses outlook andymore?? Really?? There is hotmail with windows live which is really great because anywhere you are from any computer you have access to your e-mail and other data just as you would have had on Outlook. If you really need a program like that then use Thunderbird. See how Microsoft supports open source!
Now to the original question, 7 and Vista are similar but there are many advantages to 7. My laptop had a big speed improvement and gave a longer battery life while doing it. My personal experience on my laptop but applications open faster, the pc shuts down faster, logs in faster. The look and feel are really awesome and there are some really useful funcionality features as well...