Anyone know how to totally format the dell 1545 inspiron laptop, with default empty hardisk without partition?

In my dell inspiron 1545 i can not install the windows 7 32 bit os, because it shows that the partition is dynamic,... i need to change that partition to default... anyone know how to format a hard disk from boot level to clear the datas.. i tried DBAN but it was worthless.. that i cant clear the hard disk .. i tried the win7 installation through the USB pendrive.. and the pendrive is working correctly with other laptops... please solve my problem.. how to install the os...