Hrmm. if you arent comfortable with taking your computer apart I suggest you buy another psu from newegg.com (Antec Tru430w) and either A) Take it to a local shop and have them install it. or B) Get a friend to do it for a 6-pack
If you know what you are doing it takes about 10 minutes. If you are semi-comfortable and willing to learn about computers I suggest you do it yourself.
Just remember, follow all the cords from the psu and remember what hardware required plugs. You cant really mess up, unless you forget to plug something in, but it wont hurt anything. Just do it with caution and you will be ok. PM me if you would like me to go into great detail on how to go about this.