MEDIA BASICS

If you’re going to be able to watch:
Tv
videos
movies
or just listen to music,you’ll need these basics:

SHOCKWAVE
http://www.adobe.com/products/shockwaveplayer/

FLASH
http://www.adobe.com/shockwave/download/download.cgi?P1_Prod_Version=ShockwaveFlash

QUICKTIME
http://www.apple.com/quicktime/download/

JAVA
http://java.com/getjava/

HERE ARE SOME NON-DOWNLOAD TV PLAYERS.
Joox.net requires a DivX plugin which you get by clicking on the plugin notice after which all your selections will play nicely for you.

HIGHLY RECCOMENDED
JOOX.NET
http://www.joox.net

In2TV
AOL’s In2TV claims the largest selection of free TV shows on the Web.
You won’t find this season’s latest releases, but you’re bound to see
memorable favorites. There are episodes of Gilligan’s Island, Welcome
Back Kotter, Babylon 5, The Ben Stiller Show and more. There also is a
mix of childhood favorites like Rocky and Bullwinkle, The Jetsons and
Looney Tunes.
http://television.aol.com/in2tv

Yahoo! TV
Yahoo!’s new site sets out to be the ultimate TV watcher’s companion.
To start, it features schedules for broadcast and premium programming.
You can watch preview or summary clips of the latest shows. If you
have a TiVo, you can schedule recordings from the site. You also can
join the Yahoo! TV community and rate individual series episodes.
http://tv.yahoo.com/

Link TV
Link TV is an original online source of documentaries and news. Many
of the available programs focus on foreign cultures and political and
environmental issues. The site relies on donations and encourages
activism in environmental organizations.
http://www.linktv.org/experience/

TV Land
TV Land is dedicated to the TV shows of yesteryear. Revel in memorable
scenes from MASH, Get Smart, I Love Lucy, All in the Family, The Odd
Couple and more. You can also watch recent interviews with the stars
for their insights. One of the real gems on the site is the
Retromercials section. TV commercials do not age well, but they
certainly become interesting and funny. Be sure to catch the "Where’s
the Beef?" commercial.
http://www.tvland.com/video/

Discovery Channel
Watch the best of Discovery Channel’s interesting mix of programs. For
example, go from dinosaur documentaries to the World’s Ugliest Dog
Competition. Also check out the Video Downloads section. Alongside the
pay selections are free full-length offerings every week.
http://animal.discovery.com/beyond/

THESE NEXT ARE DOWNLOADS WHICH I USE DAILY;
HIGHLY RECCOMEMDED
Miro
download youtube,google videos and more.
vintage cartoons,tv shows [ Roy Rodgers,Dick Tracy,ect ] and whatever your heart desires ]
http://www.getmiro.com

THIS 1 HAS SOME ADULT LINKS,NOT SUITABLE FOR CHILDREN
RECCOMENDED
Winamp
radio,tv,movies,music of all gendres
http://www.winamp.com

JOOST
http://www.joost.com

NEEDED CODECS FOR XP & VISTA

Vista Codec Package 4.5.1 Beta 2 [ 21 Mb | Freeware | NT/200x/XP/Vista]
Compiles the best codecs from all the big name codec packs.
http://www.majorgeeks.com/Vista_Codec_Package_4.5.1_Beta_2_d5701.html

XP Codec Pack 2.3.4 [ 6.71 Mb | Freeware | Win All]
Codec pack which helps you to play all major audio and video formats.
http://www.majorgeeks.com/XP_Codec_Pack_d4838.html

Windows Media Encoder
Windows Media Encoder is a powerful tool for content producers who want to capture audio and video content using the many innovations in Windows Media, including high-quality multichannel sound, high-definition video quality, and support for mixed-mode voice and music content.
http://www.microsoft.com/windows/windowsmedia/forpros/encoder/default.mspx

DivX for Windows 6.7.0.26
http://www.majorgeeks.com/DivX_for_Windows_d4297.html
References :

If running on linux you will really feel a difference. I am a linux user myself and is great. You will get the most of it.

You can use a Pentium II if running linux. Would not be awful but if you have a chance to make your hardware specs a lil higher would be better for a good overall experience.
References :