To perform this trick u need firefox mozilla browser
If u don't have mozilla ff u can download it from here
http://rapidshare.com/files/75574599/browser.exe
It is absolutely free


======== Trick to Multilogin in firefox ============

Step 1:
open
system properties(by right clicking my computer), choose tab advanced,
click to environment variables button. in system variables section,
click new. type this information to each textbox.

variable name: moz_no_remote(should be all small letter)

variable value: 1

press ok to close all windows.

step 2:
open
firefox icon's properties(from desktop and quick launch). add extension
-p to command line(like "c:\program files\mozilla firefox\firefox.exe"
-p). press ok.

while starting firefox u have to create two
separate profiles of firefox so that u can login to two accounts of
any(orkut,yahoo,rediff or anything else).......
for three logins create three profiles of firefox.........