In how many ways we can improve system speed. I want to know maximum methods. Is there any book regarding this things? And how can I get command on the win-xp and window-7? I want to maximum settings and changes in those OS, please help me.....

Lol....you don't want much do you ? 12-years of experience with XP and 5 or so with win7.....yikes !

Try Black Viper's website at :

Black Viper www blackviper com

lots of great info there. ...

Note : There is a LOT of BAD 'optimizing' advice and information out there for XP; so do not be surprised if nothing helps at this point.
M$ has slowly been bloating XP 'till the updates stopped, and now it takes a 2-core with 4Gigs of RAM to make it run 'fast'. A Dual-Core with 2GB will run it OK now. I have an old single-Core Dell with 1GB(that's all it will take,) and it sux, but it's as good as it will get. Boots in 25 secs but with Anti-virus on it, it cannot handle many simultaneous window...and the last few google updates also have been bad for speed (30-sec minimum open times for Chrome.)