There are two ways you can go about getting a mac-like email notification.
The first is to use Object Dock
. This is an OSX-ish doc that has many, many plugins and applets... including one for email.
The second, is to browse through the Windows 7 gadget library for a desktop gadget that does what you are looking for. Maybe one like this
. The only problem with Win7 desktop gadgets is that some of them are lacking in the quality area. However, you may find one that does what you need and does it well.