Well I just installed winxp pro but unfortunately i can't find any microsoft word,powerpoint,excel anywhere in program files.I went to microsoft.com but I could only find add-ons.If anyone knows the exact site address , I think someone should copy and paste here...

Also unfortunately, those are all parts of Microsoft Office, which costs extra. Unless you want to pay $150-$400 (give or take), you might want to try the free OpenOffice.org suite; the just-released version 1.1 is much faster than the 1.0.x versions:
http://www.OpenOffice.org

While not perfect, it does have some nice features including very good compatibility with MS Office formats, the ability to save in PDF and SWF formats and more--and it's free. I use it as my primary office suite under both Windows and Linux.