Most of you have gmail on web and enjoyed it. Gmail does almost everything it needs to right from the web, but it could use a few extra things for when you're not in the browser.using on desktop can be more interesting . Minimalist Everything for Chrome can send desktop notifications, as well as set Gmail as your default mail client. Similarly, Firefox's web protocol handler will do it automatically (by asking you if you want to use Gmail whenever you hit a mailto link).
However, if you want a bit more system-wide coverage, you can install one of the following applications:
Google's Gmail Notifier:
Google has created their own Google notifier for both Mac and Windows, which sends you notifications for new email, as well as letting set Gmail as your default mail client. It'll run in your system tray or menu bar, notify you of new messages, and take you to Gmail whenever you hit a "mailto" link.
Gmail Growl:
If you use the Growl for Windows notification system, the Gmail Growl program will not only notify you of new messages, but also set Gmail as your system-wide mail client. Mac users with Growl can add the Google+Growl program to the above Google Notifier for Growl integration as well.