Microsoft has released Beta 2 of Internet Explorer 7 to the public.
Unless you are comfortble with potential problems, it is recommended that you NOT install IE 7. IE 7 is already known to cause problems with some anti-virus programs, and to not work with some online banking, and web mail applications. A mahore security issue was also announced today.
IE 7 is limited to users with Windows XP or newer, so the majority of Windows users will not be able to use it.
For a simpler, and smaller browser, try Firefox or Opera. Both are standards-compliant and fast, and have tabbed browsing, and are free.