You can download a pdf manual for the Inspiron 1525 here
http://support.dell.com/support/edocs/systems/ins1525/en/index.htmOn page 308 of that manual it tells how to enter the System Setup (BIOS).
1 Turn on (or restart) your computer.
2 When the DELL™ logo appears, press <F2> immediately.
3 If you wait too long and the operating system logo appears, continue to wait until you see the Microsoft® Windows® desktop. Then, shut down your computer and try again.
Once you're in the BIOS settings, look around for video or graphics settings. You'll probably have to navigate the selections using your keyboard, using the arrow keys, tab, Page up, Page down, Escape, and F keys.