dont use telnet, telnet sends your password over the network in plain text, wide open. anyone with a downloadable packet sniffer (some versions of linux come with ethereal) can see your password information and it actually displays it as:
user: Username
pass: password
(i've see it done).
instead use ssh. if you need an ssh client for windows, download putty:
http://the.earth.li/~sgtatham/putty/.../x86/putty.exe
no installatoin required, just put taht on your desktop and you can use that to connect to your Linux system.
to ssh from linux to linux:
ssh user@host
example, if u are trying to ssh to you linux box at 192.168.0.3 and login as the user "tux" then u would type:
ssh tux@192.168.0.3