First of all, please use
[code][/code] tags around your code, to preserve formatting and to improve readability.
Second, what exactly are the error messages you're getting? Just saying something "doesn't work" is not very helpful for diagnosing problems.
In any case, parameter expansion is done just like any other variable, so your code seems to be ok. Except for one thing. I think you perhaps want to replace the username twice in the command.
Code:
mount -t cifs -o user="$1",password="$2" //10.200.1.125/"$1" /MT
Variables should also generally be double-quoted, unless you need word-splitting or other expansion to be done on the variable contents. Not that it really matters with single-word names, but passwords could have shell-reserved characters in them.
Speaking of which, it's not secure to have a script that requires you to pass the password as a parameter. It will remain in your command history. It would be better to use a read command and have it prompt the user for input, or perhaps retrieve it from a file that only the user calling the script has read-access to.
Also, I also wouldn't cd straight into the folder without first testing that the share was successfully mounted (Hint, try a grep on /etc/mtab).
Here are a few useful bash scripting references:
http://www.linuxcommand.org/index.php
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/index.html
http://www.gnu.org/software/bash/manual/bashref.html
http://wiki.bash-hackers.org/start
By the way,
$(..) is recommended over `..`