It depends on your needs. What do you mainly use your computer for?
The main advantages of Linux over Windows are:
1) Easier to install any software - over 20,000 completely free programs that are good or better replacements for many Windows applications are availible with one click - no installers and no download websites.
2) Much faster than Windows.
3) Zero viruses and almost complete protection from spyware
4) Free. Completely free. Major new versions of Linux distributions are relaesed every six months or so with more new features than a new version of Windows.
5) Looks better than Windows. Search youtube for "Compiz". Wobby windows, transparency, multiple desktops.... much better than Vista, and thousands of free themes and icon sets that don't require hacks like Windows does to use.
Disadvantages:
1) Many games don't run. Some do, and a lot more run with Wine, which is like an emulator but with no slowdown.
2) Can be hard to find a program that does what you want. They do exist, though, it's just some of them have names that aren't like Windows.
Here are some Ubuntu Linux programs that replace Windows apps very well
Internet Explorer -> Firefox
Outlook -> Thunderbird / Evolution
MS Paint -> Kolourpaint
Word -> OpenOffice Writer
Excel -> OpenOffice Writer
Powerpoint -> OpenOffice Impress
Photoshop -> GIMP
Bittorrent -> Transmission
Windows Media Player -> Totem / VLC
MSN Messenger -> Pidgin
3) Some hardware doesn't work too well, especially some wireless chips or graphics cards. If you tell me what your computer is like, I can tell you whether it will work.
